diff --git a/main/inc/ajax/sequence.ajax.php b/main/inc/ajax/sequence.ajax.php
index 6e2bf68001..b23a39a62c 100644
--- a/main/inc/ajax/sequence.ajax.php
+++ b/main/inc/ajax/sequence.ajax.php
@@ -193,7 +193,6 @@ switch ($action) {
 
         switch ($type) {
             case 'session':
-
                 $type = SequenceResource::SESSION_TYPE;
                 $sessionInfo = api_get_session_info($id);
                 $name = $sessionInfo['name'];
@@ -207,10 +206,13 @@ switch ($action) {
                 foreach ($parents as $parentId) {
                     if ($graph->hasVertex($parentId)) {
                         $parent = $graph->getVertex($parentId);
+                        if (!$parent->hasEdgeTo($main)) {
+                            $parent->createEdgeTo($main);
+                        }
                     } else {
                         $parent = $graph->createVertex($parentId);
+                        $parent->createEdgeTo($main);
                     }
-                    $parent->createEdgeTo($main);
                 }
 
                 foreach ($parents as $parentId) {