diff --git a/src/js.h b/src/js.h
index 8f0f26044..79ce521cd 100644
--- a/src/js.h
+++ b/src/js.h
@@ -103,6 +103,9 @@ extern const int64_t    jsDefaultRequestWait;
 #define jsAckInProgress     "+WPI"
 #define jsAckTerm           "+TERM"
 
+// jsExtDomainT is used to create a StreamSource External APIPrefix
+#define jsExtDomainT "$JS.%s.API"
+
 // jsApiAccountInfo is for obtaining general information about JetStream.
 #define jsApiAccountInfo "%.*s.INFO"
 
diff --git a/src/jsm.c b/src/jsm.c
index 1fd25db59..c62fb3f83 100644
--- a/src/jsm.c
+++ b/src/jsm.c
@@ -264,8 +264,11 @@ _marshalExternalStream(jsExternalStream *external, const char *fieldName, natsBu
     IFOK(s, natsBuf_Append(buf, fieldName, -1));
     IFOK(s, natsBuf_Append(buf, "\":{\"api\":\"", -1));
     IFOK(s, natsBuf_Append(buf, external->APIPrefix, -1));
-    IFOK(s, natsBuf_Append(buf, "\",\"deliver\":\"", -1));
-    IFOK(s, natsBuf_Append(buf, external->DeliverPrefix, -1));
+    if ((s == NATS_OK) && !nats_IsStringEmpty(external->DeliverPrefix))
+    {
+        IFOK(s, natsBuf_Append(buf, "\",\"deliver\":\"", -1));
+        IFOK(s, natsBuf_Append(buf, external->DeliverPrefix, -1));
+    }
     IFOK(s, natsBuf_Append(buf, "\"}", -1));
 
     return NATS_UPDATE_ERR_STACK(s);
@@ -1061,6 +1064,95 @@ jsStreamConfig_Init(jsStreamConfig *cfg)
     return NATS_OK;
 }
 
+static void
+_restoreMirrorAndSourcesExternal(jsStreamConfig *cfg)
+{
+    int i;
+
+    // We are guaranteed that if a source's Domain is set, there was originally
+    // no External value. So free any External value and reset to NULL to
+    // restore the original setting.
+    if ((cfg->Mirror != NULL) && !nats_IsStringEmpty(cfg->Mirror->Domain))
+    {
+        _destroyExternalStream(cfg->Mirror->External);
+        cfg->Mirror->External = NULL;
+    }
+    for (i=0; i<cfg->SourcesLen; i++)
+    {
+        jsStreamSource *src = cfg->Sources[i];
+        if ((src != NULL) && !nats_IsStringEmpty(src->Domain))
+        {
+            _destroyExternalStream(src->External);
+            src->External = NULL;
+        }
+    }
+}
+
+static natsStatus
+_convertDomain(jsStreamSource *src)
+{
+    jsExternalStream *e = NULL;
+
+    e = (jsExternalStream*) NATS_CALLOC(1, sizeof(jsExternalStream));
+    if (e == NULL)
+        return nats_setDefaultError(NATS_NO_MEMORY);
+
+    if (nats_asprintf((char**) &(e->APIPrefix), jsExtDomainT, src->Domain) < 0)
+    {
+        NATS_FREE(e);
+        return nats_setDefaultError(NATS_NO_MEMORY);
+    }
+    src->External = e;
+    return NATS_OK;
+}
+
+static natsStatus
+_convertMirrorAndSourcesDomain(bool *converted, jsStreamConfig *cfg)
+{
+    natsStatus  s   = NATS_OK;
+    bool        cm  = false;
+    bool        cs  = false;
+    int         i;
+
+    *converted = false;
+
+    if ((cfg->Mirror != NULL) && !nats_IsStringEmpty(cfg->Mirror->Domain))
+    {
+        if (cfg->Mirror->External != NULL)
+            return nats_setError(NATS_INVALID_ARG, "%s", "mirror's domain and external are both set");
+        cm = true;
+    }
+    for (i=0; i<cfg->SourcesLen; i++)
+    {
+        jsStreamSource *src = cfg->Sources[i];
+        if ((src != NULL) && !nats_IsStringEmpty(src->Domain))
+        {
+            if (src->External != NULL)
+                return nats_setError(NATS_INVALID_ARG, "%s", "source's domain and external are both set");
+            cs = true;
+        }
+    }
+    if (!cm && !cs)
+        return NATS_OK;
+
+    if (cm)
+        s = _convertDomain(cfg->Mirror);
+    if ((s == NATS_OK) && cs)
+    {
+        for (i=0; (s == NATS_OK) && (i<cfg->SourcesLen); i++)
+        {
+            jsStreamSource *src = cfg->Sources[i];
+            if ((src != NULL) && !nats_IsStringEmpty(src->Domain))
+                s = _convertDomain(src);
+        }
+    }
+    if (s == NATS_OK)
+        *converted = true;
+    else
+        _restoreMirrorAndSourcesExternal(cfg);
+    return NATS_UPDATE_ERR_STACK(s);
+}
+
 static natsStatus
 _addOrUpdate(jsStreamInfo **new_si, jsStreamAction action, jsCtx *js, jsStreamConfig *cfg, jsOptions *opts, jsErrCode *errCode)
 {
@@ -1071,6 +1163,7 @@ _addOrUpdate(jsStreamInfo **new_si, jsStreamAction action, jsCtx *js, jsStreamCo
     natsConnection      *nc     = NULL;
     const char          *apiT   = NULL;
     bool                freePfx = false;
+    bool                msc     = false;
     jsOptions           o;
 
     if (errCode != NULL)
@@ -1101,6 +1194,8 @@ _addOrUpdate(jsStreamInfo **new_si, jsStreamAction action, jsCtx *js, jsStreamCo
         if (freePfx)
             NATS_FREE((char*) o.Prefix);
     }
+    if ((s == NATS_OK) && (action == jsStreamActionCreate))
+        s = _convertMirrorAndSourcesDomain(&msc, cfg);
 
     // Marshal the stream create/update request
     IFOK(s, js_marshalStreamConfig(&buf, cfg));
@@ -1111,6 +1206,12 @@ _addOrUpdate(jsStreamInfo **new_si, jsStreamAction action, jsCtx *js, jsStreamCo
     // If we got a response, check for error or return the stream info result.
     IFOK(s, _unmarshalStreamCreateResp(new_si, NULL, resp, errCode));
 
+    // If mirror and/or sources were converted for the domain, then we need
+    // to restore the original values (which will free the memory that was
+    // allocated for the conversion).
+    if (msc)
+        _restoreMirrorAndSourcesExternal(cfg);
+
     natsBuf_Destroy(buf);
     natsMsg_Destroy(resp);
     NATS_FREE(subj);
diff --git a/src/kv.c b/src/kv.c
index 9a798a538..a82826876 100644
--- a/src/kv.c
+++ b/src/kv.c
@@ -21,9 +21,11 @@
 #include "conn.h"
 #include "sub.h"
 
-static const char *kvBucketNameTmpl  = "KV_%s";
-static const char *kvSubjectsTmpl    = "$KV.%s.>";
-static const char *kvSubjectsPreTmpl = "$KV.%s.";
+static const char *kvBucketNamePre          = "KV_";
+static const char *kvBucketNameTmpl         = "KV_%s";
+static const char *kvSubjectsTmpl           = "$KV.%s.>";
+static const char *kvSubjectsPreTmpl        = "$KV.%s.";
+static const char *kvSubjectsPreDomainTmpl  = "%s.$KV.%s.";
 
 #define KV_WATCH_FOR_EVER (int64_t)(0x7FFFFFFFFFFFFFFF)
 
@@ -34,14 +36,17 @@ natsBuffer  buf;
 #define USE_JS_PREFIX   true
 #define KEY_NAME_ONLY   false
 
-#define BUILD_SUBJECT(p) \
+#define FOR_A_PUT       true
+#define NOT_FOR_A_PUT   false
+
+#define BUILD_SUBJECT(p, fp) \
 s = natsBuf_InitWithBackend(&buf, buffer, 0, sizeof(buffer)); \
 if ((p) && kv->useJSPrefix) \
 { \
     IFOK(s, natsBuf_Append(&buf, kv->js->opts.Prefix, -1)); \
     IFOK(s, natsBuf_AppendByte(&buf, '.')); \
 } \
-IFOK(s, natsBuf_Append(&buf, kv->pre, -1)); \
+IFOK(s, natsBuf_Append(&buf, ((fp) ? (kv->usePutPre ? kv->putPre : kv->pre) : kv->pre), -1)); \
 IFOK(s, natsBuf_Append(&buf, key, -1)); \
 IFOK(s, natsBuf_AppendByte(&buf, 0));
 
@@ -119,6 +124,7 @@ _freeKV(kvStore *kv)
     NATS_FREE(kv->bucket);
     NATS_FREE(kv->stream);
     NATS_FREE(kv->pre);
+    NATS_FREE(kv->putPre);
     natsMutex_Destroy(kv->mu);
     NATS_FREE(kv);
     js_release(js);
@@ -188,52 +194,38 @@ _createKV(kvStore **new_kv, jsCtx *js, const char *bucket)
     return NATS_UPDATE_ERR_STACK(s);
 }
 
-static bool
-_sameStrings(const char *s1, const char *s2)
+static natsStatus
+_changePutPrefixIfMirrorPresent(kvStore *kv, jsStreamInfo *si)
 {
-    bool s1Empty = nats_IsStringEmpty(s1);
-    bool s2Empty = nats_IsStringEmpty(s2);
+    natsStatus      s       = NATS_OK;
+    const char      *bucket = NULL;
+    jsStreamSource  *m      = si->Config->Mirror;
 
-    // Same if both empty.
-    if (s1Empty && s2Empty)
-        return true;
+    if (m == NULL)
+        return NATS_OK;
 
-    // Not same if one is empty while other is not.
-    if ((s1Empty && !s2Empty) || (!s1Empty && s2Empty))
-        return false;
+    bucket = m->Name;
+    if (strstr(m->Name, kvBucketNamePre) == m->Name)
+        bucket = m->Name + strlen(kvBucketNamePre);
 
-    // Return result of comparison of s1 and s2
-    return (strcmp(s1, s2) == 0 ? true : false);
-}
+    if ((m->External != NULL) && !nats_IsStringEmpty(m->External->APIPrefix))
+    {
+        kv->useJSPrefix = false;
 
-static bool
-_sameStreamCfg(jsStreamConfig *oc, jsStreamConfig *nc)
-{
-    // Check some of the stream's configuration properties only,
-    // the ones that we set when creating a KV stream.
-    if (!_sameStrings(oc->Description, nc->Description))
-        return false;
-    if (oc->SubjectsLen != nc->SubjectsLen)
-        return false;
-    if (!_sameStrings(oc->Subjects[0], nc->Subjects[0]))
-        return false;
-    if (oc->MaxMsgsPerSubject != nc->MaxMsgsPerSubject)
-        return false;
-    if (oc->MaxBytes != nc->MaxBytes)
-        return false;
-    if (oc->MaxAge != nc->MaxAge)
-        return false;
-    if (oc->MaxMsgSize != nc->MaxMsgSize)
-        return false;
-    if (oc->Storage != nc->Storage)
-        return false;
-    if (oc->Replicas != nc->Replicas)
-        return false;
-    if (oc->AllowRollup != nc->AllowRollup)
-        return false;
-    if (oc->DenyDelete != nc->DenyDelete)
-        return false;
-    return true;
+        NATS_FREE(kv->pre);
+        kv->pre = NULL;
+        if (nats_asprintf(&(kv->pre), kvSubjectsPreTmpl, bucket) < 0)
+            s = nats_setDefaultError(NATS_NO_MEMORY);
+        else if (nats_asprintf(&(kv->putPre), kvSubjectsPreDomainTmpl, m->External->APIPrefix, bucket) < 0)
+            s = nats_setDefaultError(NATS_NO_MEMORY);
+    }
+    else if (nats_asprintf(&(kv->putPre), kvSubjectsPreTmpl, bucket) < 0)
+            s = nats_setDefaultError(NATS_NO_MEMORY);
+
+    if (s == NATS_OK)
+        kv->usePutPre = true;
+
+    return NATS_UPDATE_ERR_STACK(s);
 }
 
 natsStatus
@@ -245,6 +237,8 @@ js_CreateKeyValue(kvStore **new_kv, jsCtx *js, kvConfig *cfg)
     kvStore         *kv     = NULL;
     char            *subject= NULL;
     jsStreamInfo    *si     = NULL;
+    const char      *omn    = NULL;
+    const char      **osn   = NULL;
     jsStreamConfig  sc;
 
     if ((new_kv == NULL) || (js == NULL) || (cfg == NULL))
@@ -274,12 +268,11 @@ js_CreateKeyValue(kvStore **new_kv, jsCtx *js, kvConfig *cfg)
         int64_t     maxBytes    = (cfg->MaxBytes == 0 ? -1 : cfg->MaxBytes);
         int32_t     maxMsgSize  = (cfg->MaxValueSize == 0 ? -1 : cfg->MaxValueSize);
         jsErrCode   jerr        = 0;
+        const char  **subjects  = (const char*[1]){subject};
 
         jsStreamConfig_Init(&sc);
         sc.Name = kv->stream;
         sc.Description = cfg->Description;
-        sc.Subjects = (const char*[1]){subject};
-        sc.SubjectsLen = 1;
         sc.MaxMsgsPerSubject = history;
         sc.MaxBytes = maxBytes;
         sc.MaxAge = cfg->TTL;
@@ -291,15 +284,106 @@ js_CreateKeyValue(kvStore **new_kv, jsCtx *js, kvConfig *cfg)
         sc.AllowDirect = true;
         sc.RePublish = cfg->RePublish;
 
+        if (cfg->Mirror != NULL)
+        {
+            jsStreamSource *m = cfg->Mirror;
+
+            if (!nats_IsStringEmpty(m->Name)
+                && (strstr(m->Name, kvBucketNamePre) != m->Name))
+            {
+                char *newName = NULL;
+                if (nats_asprintf(&newName, kvBucketNameTmpl, m->Name) < 0)
+                    s = nats_setDefaultError(NATS_NO_MEMORY);
+                else
+                {
+                    omn = m->Name;
+                    m->Name = newName;
+                }
+            }
+            sc.Mirror = m;
+            sc.MirrorDirect = true;
+        }
+        else if (cfg->SourcesLen > 0)
+        {
+            osn = (const char**) NATS_CALLOC(cfg->SourcesLen, sizeof(char*));
+            if (osn == NULL)
+                s = nats_setDefaultError(NATS_NO_MEMORY);
+
+            if (s == NATS_OK)
+            {
+                int i;
+
+                for (i=0; i<cfg->SourcesLen; i++)
+                {
+                    jsStreamSource *ss = cfg->Sources[i];
+
+                    if (ss == NULL)
+                        continue;
+
+                    // Set this regardless of error in the loop. We need it for
+                    // proper cleanup at the end.
+                    osn[i] = ss->Name;
+
+                    if ((s == NATS_OK) && !nats_IsStringEmpty(ss->Name)
+                        && (strstr(ss->Name, kvBucketNamePre) != ss->Name))
+                    {
+                        char *newName = NULL;
+
+                        if (nats_asprintf(&newName, kvBucketNameTmpl, ss->Name) < 0)
+                            s = nats_setDefaultError(NATS_NO_MEMORY);
+                        else
+                            ss->Name = newName;
+                    }
+                }
+                if (s == NATS_OK)
+                {
+                    sc.Sources = cfg->Sources;
+                    sc.SourcesLen = cfg->SourcesLen;
+                }
+            }
+        }
+        else
+        {
+            sc.Subjects = subjects;
+            sc.SubjectsLen = 1;
+        }
+
         // If connecting to a v2.7.2+, create with discard new policy
         if (natsConn_srvVersionAtLeast(kv->js->nc, 2, 7, 2))
             sc.Discard = js_DiscardNew;
 
         s = js_AddStream(&si, js, &sc, NULL, &jerr);
-        // If the stream allow direct get message calls, then we will do so.
         if (s == NATS_OK)
+        {
+            // If the stream allow direct get message calls, then we will do so.
             kv->useDirect = si->Config->AllowDirect;
+
+            s = _changePutPrefixIfMirrorPresent(kv, si);
+        }
         jsStreamInfo_Destroy(si);
+
+        // Restore original mirror/source names
+        if (omn != NULL)
+        {
+            NATS_FREE((char*) cfg->Mirror->Name);
+            cfg->Mirror->Name = omn;
+        }
+        if (osn != NULL)
+        {
+            int i;
+
+            for (i=0; i<cfg->SourcesLen; i++)
+            {
+                jsStreamSource *ss = cfg->Sources[i];
+
+                if ((ss != NULL) && (ss->Name != osn[i]))
+                {
+                    NATS_FREE((char*) ss->Name);
+                    ss->Name = osn[i];
+                }
+            }
+            NATS_FREE((char**) osn);
+        }
     }
     if (s == NATS_OK)
         *new_kv = kv;
@@ -336,6 +420,8 @@ js_KeyValue(kvStore **new_kv, jsCtx *js, const char *bucket)
         if (si->Config->MaxMsgsPerSubject < 1)
             s = nats_setError(NATS_INVALID_ARG, "%s", kvErrBadBucket);
 
+        IFOK(s, _changePutPrefixIfMirrorPresent(kv, si));
+
         jsStreamInfo_Destroy(si);
     }
 
@@ -457,7 +543,7 @@ _getEntry(kvEntry **new_entry, bool *deleted, kvStore *kv, const char *key, uint
     if (!validKey(key))
         return nats_setError(NATS_INVALID_ARG, "%s", kvErrInvalidKey);
 
-    BUILD_SUBJECT(KEY_NAME_ONLY);
+    BUILD_SUBJECT(KEY_NAME_ONLY, NOT_FOR_A_PUT);
 
     if (kv->useDirect)
     {
@@ -577,7 +663,7 @@ _putEntry(uint64_t *rev, kvStore *kv, jsPubOptions *po, const char *key, const v
     if (!validKey(key))
         return nats_setError(NATS_INVALID_ARG, "%s", kvErrInvalidKey);
 
-    BUILD_SUBJECT(USE_JS_PREFIX);
+    BUILD_SUBJECT(USE_JS_PREFIX, FOR_A_PUT);
     IFOK(s, js_Publish(ppa, kv->js, natsBuf_Data(&buf), data, len, po, NULL));
 
     if ((s == NATS_OK) && (rev != NULL))
@@ -680,7 +766,7 @@ _delete(kvStore *kv, const char *key, bool purge, kvPurgeOptions *opts)
     if (!validKey(key))
         return nats_setError(NATS_INVALID_ARG, "%s", kvErrInvalidKey);
 
-    BUILD_SUBJECT(USE_JS_PREFIX);
+    BUILD_SUBJECT(USE_JS_PREFIX, FOR_A_PUT);
     IFOK(s, natsMsg_Create(&msg, natsBuf_Data(&buf), NULL, NULL, 0));
     if (s == NATS_OK)
     {
@@ -793,6 +879,7 @@ kvStore_PurgeDeletes(kvStore *kv, kvPurgeOptions *opts)
         for (; h != NULL; )
         {
             natsBuf_Reset(&buf);
+            // Use kv->pre here, always.
             IFOK(s, natsBuf_Append(&buf, kv->pre, -1));
             IFOK(s, natsBuf_Append(&buf, h->key, -1));
             IFOK(s, natsBuf_AppendByte(&buf, '\0'));
@@ -899,6 +986,7 @@ kvWatcher_Next(kvEntry **new_entry, kvWatcher *w, int64_t timeout)
         }
         w->refs--;
 
+        // Use kv->pre here, always.
         if ((s == NATS_OK) && (strlen(msg->subject) <= strlen(w->kv->pre)))
             s = nats_setError(NATS_ERR, "invalid update's subject '%s'", msg->subject);
 
@@ -988,7 +1076,7 @@ kvStore_Watch(kvWatcher **new_watcher, kvStore *kv, const char *key, kvWatchOpti
     w->kv = kv;
     w->refs = 1;
 
-    BUILD_SUBJECT(KEY_NAME_ONLY);
+    BUILD_SUBJECT(KEY_NAME_ONLY, NOT_FOR_A_PUT);
     IFOK(s, natsMutex_Create(&(w->mu)));
     if (s == NATS_OK)
     {
@@ -1005,6 +1093,9 @@ kvStore_Watch(kvWatcher **new_watcher, kvStore *kv, const char *key, kvWatchOpti
             if (opts->IgnoreDeletes)
                 w->ignoreDel = true;
         }
+        // Need to explicitly bind to the stream here because the subject
+        // we construct may not help find the stream when using mirrors.
+        so.Stream = kv->stream;
         s = js_SubscribeSync(&(w->sub), kv->js, natsBuf_Data(&buf), NULL, &so, NULL);
         IFOK(s, natsSubscription_SetPendingLimits(w->sub, -1, -1));
         if (s == NATS_OK)
diff --git a/src/nats.h b/src/nats.h
index 00112540e..bfb1c90cd 100644
--- a/src/nats.h
+++ b/src/nats.h
@@ -375,6 +375,10 @@ typedef struct jsStreamSource
         int64_t                 OptStartTime;   ///< UTC time expressed as number of nanoseconds since epoch.
         const char              *FilterSubject;
         jsExternalStream        *External;
+        // Domain and External are mutually exclusive.
+        // If Domain is set, an External value will be created with
+        // the APIPrefix constructed based on the Domain value.
+        const char              *Domain;
 
 } jsStreamSource;
 
@@ -1189,6 +1193,9 @@ typedef struct kvConfig
         jsStorageType   StorageType;
         int             Replicas;
         jsRePublish     *RePublish;
+        jsStreamSource  *Mirror;
+        jsStreamSource  **Sources;
+        int             SourcesLen;
 
 } kvConfig;
 
diff --git a/src/natsp.h b/src/natsp.h
index 8385e4844..fb6dde262 100644
--- a/src/natsp.h
+++ b/src/natsp.h
@@ -433,6 +433,8 @@ struct __kvStore
     char                *bucket;
     char                *stream;
     char                *pre;
+    char                *putPre;
+    bool                usePutPre;
     bool                useJSPrefix;
     bool                useDirect;
 
diff --git a/test/list.txt b/test/list.txt
index 38f5138ef..83690fdd8 100644
--- a/test/list.txt
+++ b/test/list.txt
@@ -253,6 +253,7 @@ KeyValueCrossAccount
 KeyValueDiscardOldToNew
 KeyValueRePublish
 KeyValueMirrorDirectGet
+KeyValueMirrorCrossDomains
 StanPBufAllocator
 StanConnOptions
 StanSubOptions
diff --git a/test/test.c b/test/test.c
index c1834a502..36c117ce9 100644
--- a/test/test.c
+++ b/test/test.c
@@ -5509,7 +5509,8 @@ _stopServer(natsPid pid)
     CloseHandle(pid->hThread);
 
     natsMutex_Lock(slMu);
-    natsHash_Remove(slMap, (int64_t) pid);
+    if (slMap != NULL)
+        natsHash_Remove(slMap, (int64_t) pid);
     natsMutex_Unlock(slMu);
 
     free(pid);
@@ -5614,7 +5615,8 @@ _startServerImpl(const char *serverExe, const char *url, const char *cmdLineOpts
     }
 
     natsMutex_Lock(slMu);
-    natsHash_Set(slMap, (int64_t) pid, NULL, NULL);
+    if (slMap != NULL)
+        natsHash_Set(slMap, (int64_t) pid, NULL, NULL);
     natsMutex_Unlock(slMu);
 
     return (natsPid) pid;
@@ -5644,7 +5646,8 @@ _stopServer(natsPid pid)
     waitpid(pid, &status, 0);
 
     natsMutex_Lock(slMu);
-    natsHash_Remove(slMap, (int64_t) pid);
+    if (slMap != NULL)
+        natsHash_Remove(slMap, (int64_t) pid);
     natsMutex_Unlock(slMu);
 }
 
@@ -5720,7 +5723,8 @@ _startServerImpl(const char *serverExe, const char *url, const char *cmdLineOpts
     }
 
     natsMutex_Lock(slMu);
-    natsHash_Set(slMap, (int64_t) pid, NULL, NULL);
+    if (slMap != NULL)
+        natsHash_Set(slMap, (int64_t) pid, NULL, NULL);
     natsMutex_Unlock(slMu);
 
     // parent, return the child's PID back.
@@ -22683,6 +22687,8 @@ test_JetStreamMgtStreams(void)
     jsStreamInfoList    *siList = NULL;
     jsStreamNamesList   *snList = NULL;
     int                 count   = 0;
+    jsStreamSource      ss;
+    jsExternalStream    se;
     jsOptions           o;
     int                 i;
 
@@ -23107,6 +23113,7 @@ test_JetStreamMgtStreams(void)
                             natsMsg_GetData(resp),
                             natsMsg_GetDataLength(resp)) == 0));
     jsStreamInfo_Destroy(si);
+    si = NULL;
     natsMsg_Destroy(resp);
     resp = NULL;
 
@@ -23150,6 +23157,7 @@ test_JetStreamMgtStreams(void)
                 && (strcmp(si->Config->Subjects[0], "foo.>") == 0)
                 && (strcmp(si->Config->Subjects[1], "bar.*") == 0));
     jsStreamInfo_Destroy(si);
+    si = NULL;
 
     test("List stream infos (bad args): ");
     s = js_Streams(NULL, js, NULL, NULL);
@@ -23286,6 +23294,35 @@ test_JetStreamMgtStreams(void)
     s = js_StreamNames(&snList, js, &o, &jerr);
     testCond((s == NATS_NOT_FOUND) && (snList == NULL));
 
+    test("Mirror domain and external set error: ");
+    jsStreamConfig_Init(&cfg);
+    cfg.Name = "MDESET";
+    jsStreamSource_Init(&ss);
+    ss.Domain = "Domain";
+    jsExternalStream_Init(&se);
+    se.DeliverPrefix = "some.prefix";
+    ss.External = &se;
+    cfg.Mirror = &ss;
+    s = js_AddStream(&si, js, &cfg, NULL, NULL);
+    testCond((s == NATS_INVALID_ARG) && (si == NULL)
+                && (strstr(nats_GetLastError(NULL), "domain and external are both set") != NULL));
+    nats_clearLastError();
+
+    test("Source domain and external set error: ");
+    jsStreamConfig_Init(&cfg);
+    cfg.Name = "SDESET";
+    jsStreamSource_Init(&ss);
+    ss.Domain = "Domain";
+    jsExternalStream_Init(&se);
+    se.DeliverPrefix = "some.prefix";
+    ss.External = &se;
+    cfg.Sources = (jsStreamSource*[1]){&ss};
+    cfg.SourcesLen = 1;
+    s = js_AddStream(&si, js, &cfg, NULL, NULL);
+    testCond((s == NATS_INVALID_ARG) && (si == NULL)
+                && (strstr(nats_GetLastError(NULL), "domain and external are both set") != NULL));
+    nats_clearLastError();
+
     JS_TEARDOWN;
 }
 
@@ -31222,6 +31259,356 @@ test_KeyValueMirrorDirectGet(void)
     JS_TEARDOWN;
 }
 
+static natsStatus
+_connectToHubAndCheckLeaf(natsConnection **hub, natsConnection *lnc)
+{
+    natsStatus          s       = NATS_OK;
+    natsConnection      *nc     = NULL;
+    natsSubscription    *sub    = NULL;
+    int                 i;
+
+    s = natsConnection_ConnectTo(&nc, NATS_DEFAULT_URL);
+    IFOK(s, natsConnection_SubscribeSync(&sub, nc, "check"));
+    IFOK(s, natsConnection_Flush(nc));
+    if (s == NATS_OK)
+    {
+        for (i=0; i<10; i++)
+        {
+            s = natsConnection_PublishString(lnc, "check", "hello");
+            if (s == NATS_OK)
+            {
+                natsMsg *msg = NULL;
+                s = natsSubscription_NextMsg(&msg, sub, 500);
+                natsMsg_Destroy(msg);
+                if (s == NATS_OK)
+                    break;
+            }
+        }
+    }
+    natsSubscription_Destroy(sub);
+    if (s == NATS_OK)
+        *hub = nc;
+    else
+        natsConnection_Destroy(nc);
+    return s;
+}
+
+static void
+test_KeyValueMirrorCrossDomains(void)
+{
+    natsStatus          s;
+    natsConnection      *nc = NULL;
+    natsConnection      *lnc= NULL;
+    jsCtx               *js = NULL;
+    jsCtx               *ljs= NULL;
+    jsCtx               *rjs= NULL;
+    natsPid             pid = NATS_INVALID_PID;
+    natsPid             pid2= NATS_INVALID_PID;
+    jsOptions           o;
+    jsErrCode           jerr = 0;
+    char                datastore[256]  = {'\0'};
+    char                datastore2[256] = {'\0'};
+    char                cmdLine[1024]   = {'\0'};
+    char                confFile[256]   = {'\0'};
+    char                lconfFile[256]  = {'\0'};
+    kvStore             *kv     = NULL;
+    kvStore             *lkv    = NULL;
+    kvStore             *mkv    = NULL;
+    kvStore             *rkv    = NULL;
+    kvEntry             *e      = NULL;
+    jsStreamInfo        *si     = NULL;
+    kvWatcher           *w      = NULL;
+    int                 ok      = 0;
+    kvPurgeOptions      po;
+    kvConfig            kvc;
+    jsStreamSource      src;
+    int                 i;
+
+    ENSURE_JS_VERSION(2, 9, 0);
+
+    _makeUniqueDir(datastore, sizeof(datastore), "datastore_");
+    _createConfFile(confFile, sizeof(confFile),
+        "server_name: HUB\n"\
+        "listen: 127.0.0.1:4222\n"\
+        "jetstream: { domain: HUB }\n"\
+        "leafnodes { listen: 127.0.0.1:7422 }\n");
+
+    test("Start hub: ");
+    snprintf(cmdLine, sizeof(cmdLine), "-js -sd %s -c %s", datastore, confFile);
+    pid = _startServer("nats://127.0.0.1:4222", cmdLine, true);
+    CHECK_SERVER_STARTED(pid);
+    testCond(true);
+
+    _makeUniqueDir(datastore2, sizeof(datastore2), "datastore_");
+    _createConfFile(lconfFile, sizeof(lconfFile),
+        "server_name: LEAF\n"\
+        "listen: 127.0.0.1:4223\n"\
+        "jetstream: { domain: LEAF }\n"\
+        "leafnodes {\n"\
+        "   remotes = [ { url: leaf://127.0.0.1:7422 } ]\n"\
+        "}\n");
+
+    test("Start leaf: ");
+    snprintf(cmdLine, sizeof(cmdLine), "-js -sd %s -c %s", datastore, lconfFile);
+    pid2 = _startServer("nats://127.0.0.1:4223", cmdLine, true);
+    CHECK_SERVER_STARTED(pid2);
+    testCond(true);
+
+    test("Connect to leaf: ");
+    s = natsConnection_ConnectTo(&lnc, "nats://127.0.0.1:4223");
+    testCond(s == NATS_OK);
+
+    test("Get context: ");
+    s = natsConnection_JetStream(&ljs, lnc, NULL);
+    testCond(s == NATS_OK);
+
+    test("Connect to hub and check connectivity through leaf: ");
+    s = _connectToHubAndCheckLeaf(&nc, lnc);
+    testCond(s == NATS_OK);
+
+    test("Get context: ");
+    s = natsConnection_JetStream(&js, nc, NULL);
+    testCond(s == NATS_OK);
+
+    test("Create KV value: ");
+    kvConfig_Init(&kvc);
+    kvc.Bucket = "TEST";
+    s = js_CreateKeyValue(&kv, js, &kvc);
+    testCond(s == NATS_OK);
+
+    test("Put keys: ");
+    s = kvStore_PutString(NULL, kv, "name", "derek");
+    IFOK(s, kvStore_PutString(NULL, kv, "age", "22"));
+    testCond(s == NATS_OK);
+
+    test("Create KV: ");
+    kvConfig_Init(&kvc);
+    kvc.Bucket = "MIRROR";
+    jsStreamSource_Init(&src);
+    src.Name = "TEST";
+    src.Domain = "HUB";
+    kvc.Mirror = &src;
+    s = js_CreateKeyValue(&lkv, ljs, &kvc);
+    testCond(s == NATS_OK);
+
+    test("Check config not changed: ");
+    testCond((strcmp(kvc.Bucket, "MIRROR") == 0)
+                && (kvc.Mirror != NULL)
+                && (strcmp(kvc.Mirror->Name, "TEST") == 0)
+                && (strcmp(kvc.Mirror->Domain, "HUB") == 0)
+                && (kvc.Mirror->External == NULL));
+
+    test("Get stream info: ");
+    s = js_GetStreamInfo(&si, ljs, "KV_MIRROR", NULL, &jerr);
+    testCond((s == NATS_OK) && (si != NULL) && (jerr == 0));
+
+    test("Check mirror direct: ");
+    testCond(si->Config->MirrorDirect);
+    jsStreamInfo_Destroy(si);
+    si = NULL;
+
+    test("Check mirror syncs: ");
+    for (i=0; i<10; i++)
+    {
+        s = js_GetStreamInfo(&si, ljs, "KV_MIRROR", NULL, NULL);
+        if (s != NATS_OK)
+            break;
+
+        if (si->State.Msgs != 2)
+            s = NATS_ERR;
+
+        jsStreamInfo_Destroy(si);
+        si = NULL;
+        if (s == NATS_OK)
+            break;
+        nats_Sleep(250);
+    }
+    testCond(s == NATS_OK);
+
+    // Bind locally from leafnode and make sure both get and put work.
+    test("Leaf KV: ");
+    s = js_KeyValue(&mkv, ljs, "MIRROR");
+    testCond(s == NATS_OK);
+
+    test("Put key: ");
+    s = kvStore_PutString(NULL, mkv, "name", "rip");
+    testCond(s == NATS_OK);
+
+    test("Get key: ");
+    s = kvStore_Get(&e, mkv, "name");
+    if ((s == NATS_OK) && (e != NULL))
+        s = (strcmp(kvEntry_ValueString(e), "rip") == 0 ? NATS_OK : NATS_ERR);
+    testCond(s == NATS_OK);
+    kvEntry_Destroy(e);
+    e = NULL;
+
+    test("Get context for HUB: ");
+    jsOptions_Init(&o);
+    o.Domain = "HUB";
+    s = natsConnection_JetStream(&rjs, lnc, &o);
+    testCond(s == NATS_OK);
+
+    test("Get KV: ");
+    s = js_KeyValue(&rkv, rjs, "TEST");
+    testCond(s == NATS_OK);
+
+    test("Put key: ");
+    s = kvStore_PutString(NULL, rkv, "name", "ivan");
+    testCond(s == NATS_OK);
+
+    test("Get key: ");
+    s = kvStore_Get(&e, rkv, "name");
+    if ((s == NATS_OK) && (e != NULL))
+        s = (strcmp(kvEntry_ValueString(e), "ivan") == 0 ? NATS_OK : NATS_ERR);
+    testCond(s == NATS_OK);
+    kvEntry_Destroy(e);
+    e = NULL;
+
+    test("Shutdown hub: ");
+    jsCtx_Destroy(js);
+    kvStore_Destroy(kv);
+    natsConnection_Destroy(nc);
+    nc = NULL;
+    _stopServer(pid);
+    pid = NATS_INVALID_PID;
+    testCond(true);
+    nats_Sleep(500);
+
+    test("Get key: ");
+    // Use mkv here, not rkv.
+    s = kvStore_Get(&e, mkv, "name");
+    if ((s == NATS_OK) && (e != NULL))
+        s = (strcmp(kvEntry_ValueString(e), "ivan") == 0 ? NATS_OK : NATS_ERR);
+    testCond(s == NATS_OK);
+    kvEntry_Destroy(e);
+    e = NULL;
+
+    test("Create watcher (name): ");
+    s = kvStore_Watch(&w, mkv, "name", NULL);
+    testCond(s == NATS_OK);
+
+    test("Check watcher: ");
+    s = kvWatcher_Next(&e, w, 1000);
+    if (s == NATS_OK)
+    {
+        if ((strcmp(kvEntry_Key(e), "name") != 0) || (strcmp(kvEntry_ValueString(e), "ivan") != 0))
+            s = NATS_ERR;
+        kvEntry_Destroy(e);
+        e = NULL;
+    }
+    IFOK(s, kvWatcher_Next(&e, w, 1000));
+    if (s == NATS_OK)
+    {
+        if ((kvEntry_Key(e) != NULL) || (kvEntry_ValueString(e) != NULL))
+            s = NATS_ERR;
+        kvEntry_Destroy(e);
+        e = NULL;
+    }
+    testCond(s == NATS_OK);
+
+    test("No more: ");
+    s = kvWatcher_Next(&e, w, 250);
+    testCond((s == NATS_TIMEOUT) && (e == NULL));
+    nats_clearLastError();
+
+    kvWatcher_Destroy(w);
+    w = NULL;
+
+    test("Create watcher (all): ")
+    s = kvStore_WatchAll(&w, mkv, NULL);
+    testCond((s == NATS_OK) && (w != NULL));
+
+    test("Check watcher: ");
+    s = kvWatcher_Next(&e, w, 1000);
+    if (s == NATS_OK)
+    {
+        if ((strcmp(kvEntry_Key(e), "age") != 0) || (strcmp(kvEntry_ValueString(e), "22") != 0))
+            s = NATS_ERR;
+        kvEntry_Destroy(e);
+        e = NULL;
+    }
+    IFOK(s, kvWatcher_Next(&e, w, 1000));
+    if (s == NATS_OK)
+    {
+        if ((strcmp(kvEntry_Key(e), "name") != 0) || (strcmp(kvEntry_ValueString(e), "ivan") != 0))
+            s = NATS_ERR;
+        kvEntry_Destroy(e);
+        e = NULL;
+    }
+    IFOK(s, kvWatcher_Next(&e, w, 1000));
+    if (s == NATS_OK)
+    {
+        if ((kvEntry_Key(e) != NULL) || (kvEntry_ValueString(e) != NULL))
+            s = NATS_ERR;
+        kvEntry_Destroy(e);
+        e = NULL;
+    }
+    testCond(s == NATS_OK);
+
+    test("No more: ");
+    s = kvWatcher_Next(&e, w, 250);
+    testCond((s == NATS_TIMEOUT) && (e == NULL));
+    nats_clearLastError();
+
+    test("Restart hub: ");
+    snprintf(cmdLine, sizeof(cmdLine), "-js -sd %s -c %s", datastore, confFile);
+    pid = _startServer("nats://127.0.0.1:4222", cmdLine, true);
+    CHECK_SERVER_STARTED(pid);
+    testCond(true);
+
+    test("Connect to hub and check connectivity through leaf: ");
+    s = _connectToHubAndCheckLeaf(&nc, lnc);
+    testCond(s == NATS_OK);
+
+    test("Delete keys: ");
+    s = kvStore_Delete(mkv, "age");
+    IFOK(s, kvStore_Delete(mkv, "name"));
+    testCond(s == NATS_OK);
+
+    test("Check mirror syncs: ");
+    for (i=0; (ok != 2) && (i < 10); i++)
+    {
+        if (kvWatcher_Next(&e, w, 1000) == NATS_OK)
+        {
+            if (((strcmp(kvEntry_Key(e), "age") == 0) || (strcmp(kvEntry_Key(e), "name") == 0))
+                && (kvEntry_Operation(e) == kvOp_Delete))
+            {
+                ok++;
+            }
+            kvEntry_Destroy(e);
+            e = NULL;
+        }
+    }
+    testCond((s == NATS_OK) && (ok == 2));
+
+    test("Purge deletes: ");
+    kvPurgeOptions_Init(&po);
+    po.DeleteMarkersOlderThan = -1;
+    s = kvStore_PurgeDeletes(mkv, &po);
+    testCond(s == NATS_OK);
+
+    nats_clearLastError();
+    test("Check stream: ");
+    s = js_GetStreamInfo(&si, ljs, "KV_MIRROR", NULL, NULL);
+    testCond((s == NATS_OK) && (si != NULL) && (si->State.Msgs == 0));
+    jsStreamInfo_Destroy(si);
+
+    kvWatcher_Destroy(w);
+    natsConnection_Destroy(nc);
+    kvStore_Destroy(rkv);
+    kvStore_Destroy(mkv);
+    kvStore_Destroy(lkv);
+    jsCtx_Destroy(rjs);
+    jsCtx_Destroy(ljs);
+    natsConnection_Destroy(lnc);
+    _stopServer(pid2);
+    rmtree(datastore2);
+    _stopServer(pid);
+    rmtree(datastore);
+    remove(confFile);
+    remove(lconfFile);
+}
+
 #if defined(NATS_HAS_STREAMING)
 
 static int
@@ -33690,6 +34077,7 @@ static testInfo allTests[] =
     {"KeyValueDiscardOldToNew",         test_KeyValueDiscardOldToNew},
     {"KeyValueRePublish",               test_KeyValueRePublish},
     {"KeyValueMirrorDirectGet",         test_KeyValueMirrorDirectGet},
+    {"KeyValueMirrorCrossDomains",      test_KeyValueMirrorCrossDomains},
 
 #if defined(NATS_HAS_STREAMING)
     {"StanPBufAllocator",               test_StanPBufAllocator},
@@ -33855,16 +34243,34 @@ int main(int argc, char **argv)
 
     // Shutdown servers that are still running likely due to failed test
     {
+        natsHash     *pids = NULL;
         natsHashIter iter;
         int64_t      key;
 
-        natsMutex_Lock(slMu);
-        natsHashIter_Init(&iter, slMap);
+        if (natsHash_Create(&pids, 16) == NATS_OK)
+        {
+            natsMutex_Lock(slMu);
+            natsHashIter_Init(&iter, slMap);
+            while (natsHashIter_Next(&iter, &key, NULL))
+            {
+                natsHash_Set(pids, key, NULL, NULL);
+                natsHashIter_RemoveCurrent(&iter);
+            }
+            natsHashIter_Done(&iter);
+            natsHash_Destroy(slMap);
+            slMap = NULL;
+            natsMutex_Unlock(slMu);
 
-        while (natsHashIter_Next(&iter, &key, NULL))
-            _stopServer((natsPid) key);
+            natsHashIter_Init(&iter, pids);
+            while (natsHashIter_Next(&iter, &key, NULL))
+                _stopServer((natsPid) key);
 
-        natsHash_Destroy(slMap);
+            natsHash_Destroy(pids);
+        }
+        else
+        {
+            natsHash_Destroy(slMap);
+        }
         natsMutex_Destroy(slMu);
     }