diff --git a/chain/sync_manager.go b/chain/sync_manager.go
index c7fdea7261e..c25068f60c2 100644
--- a/chain/sync_manager.go
+++ b/chain/sync_manager.go
@@ -2,7 +2,9 @@ package chain
 
 import (
 	"context"
+	"os"
 	"sort"
+	"strings"
 	"sync"
 
 	"github.com/filecoin-project/lotus/chain/types"
@@ -11,6 +13,14 @@ import (
 
 const BootstrapPeerThreshold = 2
 
+var coalesceForksParents = false
+
+func init() {
+	if os.Getenv("LOTUS_SYNC_REL_PARENT") == "yes" {
+		coalesceForksParents = true
+	}
+}
+
 const (
 	BSStateInit      = 0
 	BSStateSelected  = 1
@@ -152,6 +162,19 @@ func newSyncTargetBucket(tipsets ...*types.TipSet) *syncTargetBucket {
 	return &stb
 }
 
+func (sbs *syncBucketSet) String() string {
+	var bStrings []string
+	for _, b := range sbs.buckets {
+		var tsStrings []string
+		for _, t := range b.tips {
+			tsStrings = append(tsStrings, t.String())
+		}
+		bStrings = append(bStrings, "["+strings.Join(tsStrings, ",")+"]")
+	}
+
+	return "{" + strings.Join(bStrings, ";") + "}"
+}
+
 func (sbs *syncBucketSet) RelatedToAny(ts *types.TipSet) bool {
 	for _, b := range sbs.buckets {
 		if b.sameChainAs(ts) {
@@ -198,13 +221,17 @@ func (sbs *syncBucketSet) removeBucket(toremove *syncTargetBucket) {
 }
 
 func (sbs *syncBucketSet) PopRelated(ts *types.TipSet) *syncTargetBucket {
+	var bOut *syncTargetBucket
 	for _, b := range sbs.buckets {
 		if b.sameChainAs(ts) {
 			sbs.removeBucket(b)
-			return b
+			if bOut == nil {
+				bOut = &syncTargetBucket{}
+			}
+			bOut.tips = append(bOut.tips, b.tips...)
 		}
 	}
-	return nil
+	return bOut
 }
 
 func (sbs *syncBucketSet) Heaviest() *types.TipSet {
@@ -224,8 +251,7 @@ func (sbs *syncBucketSet) Empty() bool {
 }
 
 type syncTargetBucket struct {
-	tips  []*types.TipSet
-	count int
+	tips []*types.TipSet
 }
 
 func (stb *syncTargetBucket) sameChainAs(ts *types.TipSet) bool {
@@ -239,12 +265,14 @@ func (stb *syncTargetBucket) sameChainAs(ts *types.TipSet) bool {
 		if ts.Parents() == t.Key() {
 			return true
 		}
+		if coalesceForksParents && ts.Parents() == t.Parents() {
+			return true
+		}
 	}
 	return false
 }
 
 func (stb *syncTargetBucket) add(ts *types.TipSet) {
-	stb.count++
 
 	for _, t := range stb.tips {
 		if t.Equals(ts) {
@@ -294,7 +322,6 @@ func (sm *syncManager) selectSyncTarget() (*types.TipSet, error) {
 }
 
 func (sm *syncManager) syncScheduler() {
-
 	for {
 		select {
 		case ts, ok := <-sm.incomingTipSets:
@@ -326,7 +353,8 @@ func (sm *syncManager) scheduleIncoming(ts *types.TipSet) {
 	var relatedToActiveSync bool
 	for _, acts := range sm.activeSyncs {
 		if ts.Equals(acts) {
-			break
+			// ignore, we are already syncing it
+			return
 		}
 
 		if ts.Parents() == acts.Key() {
@@ -376,7 +404,9 @@ func (sm *syncManager) scheduleProcessResult(res *syncResult) {
 				sm.nextSyncTarget = relbucket
 				sm.workerChan = sm.syncTargets
 			} else {
-				sm.syncQueue.buckets = append(sm.syncQueue.buckets, relbucket)
+				for _, t := range relbucket.tips {
+					sm.syncQueue.Insert(t)
+				}
 			}
 			return
 		}
diff --git a/chain/sync_manager_test.go b/chain/sync_manager_test.go
index 269b3a62e07..709e03a4108 100644
--- a/chain/sync_manager_test.go
+++ b/chain/sync_manager_test.go
@@ -67,6 +67,69 @@ func assertGetSyncOp(t *testing.T, c chan *syncOp, ts *types.TipSet) {
 	}
 }
 
+func TestSyncManagerEdgeCase(t *testing.T) {
+	ctx := context.Background()
+
+	a := mock.TipSet(mock.MkBlock(genTs, 1, 1))
+	t.Logf("a: %s", a)
+	b1 := mock.TipSet(mock.MkBlock(a, 1, 2))
+	t.Logf("b1: %s", b1)
+	b2 := mock.TipSet(mock.MkBlock(a, 2, 3))
+	t.Logf("b2: %s", b2)
+	c1 := mock.TipSet(mock.MkBlock(b1, 2, 4))
+	t.Logf("c1: %s", c1)
+	c2 := mock.TipSet(mock.MkBlock(b2, 1, 5))
+	t.Logf("c2: %s", c2)
+	d1 := mock.TipSet(mock.MkBlock(c1, 1, 6))
+	t.Logf("d1: %s", d1)
+	e1 := mock.TipSet(mock.MkBlock(d1, 1, 7))
+	t.Logf("e1: %s", e1)
+
+	runSyncMgrTest(t, "edgeCase", 1, func(t *testing.T, sm *syncManager, stc chan *syncOp) {
+		sm.SetPeerHead(ctx, "peer1", a)
+		assertGetSyncOp(t, stc, a)
+
+		sm.SetPeerHead(ctx, "peer1", b1)
+		sm.SetPeerHead(ctx, "peer1", b2)
+		// b1 and b2 are being processed
+
+		b1op := <-stc
+		b2op := <-stc
+		if !b1op.ts.Equals(b1) {
+			b1op, b2op = b2op, b1op
+		}
+
+		sm.SetPeerHead(ctx, "peer2", c2) // c2 is put into activeSyncTips at index 0
+		sm.SetPeerHead(ctx, "peer2", c1) // c1 is put into activeSyncTips at index 1
+		sm.SetPeerHead(ctx, "peer3", b2) // b2 is related to c2 and even though it is actively synced it is put into activeSyncTips index 0
+		sm.SetPeerHead(ctx, "peer1", a)  // a is related to b2 and is put into activeSyncTips index 0
+
+		b1op.done() // b1 completes first, is related to a, so it pops activeSyncTips index 0
+		// even though correct one is index 1
+
+		b2op.done()
+		// b2 completes and is not related to c1, so it leaves activeSyncTips as it is
+
+		waitUntilAllWorkersAreDone(stc)
+
+		if len(sm.activeSyncTips.buckets) != 0 {
+			t.Errorf("activeSyncTips expected empty but got: %s", sm.activeSyncTips.String())
+		}
+	})
+}
+
+func waitUntilAllWorkersAreDone(stc chan *syncOp) {
+	for i := 0; i < 10; {
+		select {
+		case so := <-stc:
+			so.done()
+		default:
+			i++
+			time.Sleep(10 * time.Millisecond)
+		}
+	}
+}
+
 func TestSyncManager(t *testing.T) {
 	ctx := context.Background()