diff --git a/src/Security/Group.php b/src/Security/Group.php
index 87200903cdc..a8a3a5c5f11 100755
--- a/src/Security/Group.php
+++ b/src/Security/Group.php
@@ -8,6 +8,7 @@
 use SilverStripe\Forms\DropdownField;
 use SilverStripe\Forms\FieldList;
 use SilverStripe\Forms\Form;
+use SilverStripe\Forms\FormField;
 use SilverStripe\Forms\GridField\GridField;
 use SilverStripe\Forms\GridField\GridFieldAddExistingAutocompleter;
 use SilverStripe\Forms\GridField\GridFieldButtonRow;
@@ -27,6 +28,8 @@
 use SilverStripe\Forms\TabSet;
 use SilverStripe\Forms\TextareaField;
 use SilverStripe\Forms\TextField;
+use SilverStripe\Forms\TreeDropdownField;
+use SilverStripe\Forms\TreeMultiselectField;
 use SilverStripe\ORM\ArrayList;
 use SilverStripe\ORM\DataObject;
 use SilverStripe\ORM\DataQuery;
@@ -297,6 +300,35 @@ public function fieldLabels($includerelations = true)
         return $labels;
     }
 
+    public function scaffoldFormFieldForHasOne(
+        string $fieldName,
+        ?string $fieldTitle,
+        string $relationName,
+        DataObject $ownerRecord
+    ): FormField {
+        return TreeDropdownField::create($fieldName, $fieldTitle, static::class);
+    }
+
+    public function scaffoldFormFieldForHasMany(
+        string $relationName,
+        ?string $fieldTitle,
+        DataObject $ownerRecord,
+        bool &$includeInOwnTab
+    ): FormField {
+        $includeInOwnTab = false;
+        return TreeMultiselectField::create($relationName, $fieldTitle, static::class);
+    }
+
+    public function scaffoldFormFieldForManyMany(
+        string $relationName,
+        ?string $fieldTitle,
+        DataObject $ownerRecord,
+        bool &$includeInOwnTab
+    ): FormField {
+        $includeInOwnTab = false;
+        return TreeMultiselectField::create($relationName, $fieldTitle, static::class);
+    }
+
     /**
      * Get many-many relation to {@link Member},
      * including all members which are "inherited" from children groups of this record.
diff --git a/src/Security/Member.php b/src/Security/Member.php
index a8aa90e6a61..67c1fc6af3b 100644
--- a/src/Security/Member.php
+++ b/src/Security/Member.php
@@ -40,6 +40,10 @@
 use Symfony\Component\Mime\Exception\RfcComplianceException;
 use Closure;
 use RuntimeException;
+use SilverStripe\Forms\FormField;
+use SilverStripe\Forms\SearchableDropdownField;
+use SilverStripe\Forms\SearchableMultiDropdownField;
+use SilverStripe\ORM\FieldType\DBForeignKey;
 
 /**
  * The member class which represents the users of the system
@@ -1442,6 +1446,50 @@ public function fieldLabels($includerelations = true)
         return $labels;
     }
 
+    public function scaffoldFormFieldForHasOne(
+        string $fieldName,
+        ?string $fieldTitle,
+        string $relationName,
+        DataObject $ownerRecord
+    ): FormField {
+        $field = parent::scaffoldFormFieldForHasOne($fieldName, $fieldTitle, $relationName, $ownerRecord);
+        if ($field instanceof SearchableDropdownField) {
+            $field->setUseSearchContext(true);
+        }
+        return $field;
+    }
+
+    public function scaffoldFormFieldForHasMany(
+        string $relationName,
+        ?string $fieldTitle,
+        DataObject $ownerRecord,
+        bool &$includeInOwnTab
+    ): FormField {
+        $includeInOwnTab = false;
+        return $this->scaffoldFormFieldForManyRelation($relationName, $fieldTitle);
+    }
+
+    public function scaffoldFormFieldForManyMany(
+        string $relationName,
+        ?string $fieldTitle,
+        DataObject $ownerRecord,
+        bool &$includeInOwnTab
+    ): FormField {
+        $includeInOwnTab = false;
+        return $this->scaffoldFormFieldForManyRelation($relationName, $fieldTitle);
+    }
+
+    private function scaffoldFormFieldForManyRelation(string $relationName, ?string $fieldTitle): FormField
+    {
+        $list = static::get();
+        $field = SearchableMultiDropdownField::create($relationName, $fieldTitle, $list);
+        // Use the same lazyload threshold has_one relations use
+        $threshold = DBForeignKey::config()->get('dropdown_field_threshold');
+        $overThreshold = $list->count() > $threshold;
+        $field->setIsLazyLoaded($overThreshold)->setLazyLoadLimit($threshold);
+        return $field;
+    }
+
     /**
      * Users can view their own record.
      * Otherwise they'll need ADMIN or CMS_ACCESS_SecurityAdmin permissions.