diff --git a/core/attributedef/AttributeLinkedSetIndirect.php b/core/attributedef/AttributeLinkedSetIndirect.php
new file mode 100644
index 000000000..90d838647
--- /dev/null
+++ b/core/attributedef/AttributeLinkedSetIndirect.php
@@ -0,0 +1,96 @@
+<?php
+
+/**
+ * Set of objects linked to an object (n-n), and being part of its definition
+ *
+ * @package     iTopORM
+ */
+class AttributeLinkedSetIndirect extends AttributeLinkedSet
+{
+    /**
+     * Useless constructor, but if not present PHP 7.4.0/7.4.1 is crashing :( (N°2329)
+     *
+     * @see https://www.php.net/manual/fr/language.oop5.decon.php states that child constructor can be ommited
+     * @see https://bugs.php.net/bug.php?id=79010 bug solved in PHP 7.4.9
+     *
+     * @param string $sCode
+     * @param array $aParams
+     *
+     * @throws \Exception
+     * @noinspection SenselessProxyMethodInspection
+     */
+    public function __construct($sCode, $aParams)
+    {
+        parent::__construct($sCode, $aParams);
+    }
+
+    public static function ListExpectedParams()
+    {
+        return array_merge(parent::ListExpectedParams(), array("ext_key_to_remote"));
+    }
+
+    public function IsIndirect()
+    {
+        return true;
+    }
+
+    public function GetExtKeyToRemote()
+    {
+        return $this->Get('ext_key_to_remote');
+    }
+
+    public function GetEditClass()
+    {
+        return "LinkedSet";
+    }
+
+    public function DuplicatesAllowed()
+    {
+        return $this->GetOptional("duplicates", false);
+    } // The same object may be linked several times... or not...
+
+    public function GetTrackingLevel()
+    {
+        return $this->GetOptional('tracking_level',
+            MetaModel::GetConfig()->Get('tracking_level_linked_set_indirect_default'));
+    }
+
+    /**
+     * Find the corresponding "link" attribute on the target class, if any
+     *
+     * @return null | AttributeDefinition
+     * @throws \CoreException
+     */
+    public function GetMirrorLinkAttribute()
+    {
+        $oRet = null;
+        /** @var \AttributeExternalKey $oExtKeyToRemote */
+        $oExtKeyToRemote = MetaModel::GetAttributeDef($this->GetLinkedClass(), $this->GetExtKeyToRemote());
+        $sRemoteClass = $oExtKeyToRemote->GetTargetClass();
+        foreach (MetaModel::ListAttributeDefs($sRemoteClass) as $sRemoteAttCode => $oRemoteAttDef) {
+            if (!$oRemoteAttDef instanceof AttributeLinkedSetIndirect) {
+                continue;
+            }
+            if ($oRemoteAttDef->GetLinkedClass() != $this->GetLinkedClass()) {
+                continue;
+            }
+            if ($oRemoteAttDef->GetExtKeyToMe() != $this->GetExtKeyToRemote()) {
+                continue;
+            }
+            if ($oRemoteAttDef->GetExtKeyToRemote() != $this->GetExtKeyToMe()) {
+                continue;
+            }
+            $oRet = $oRemoteAttDef;
+            break;
+        }
+
+        return $oRet;
+    }
+
+    /** @inheritDoc */
+    public static function IsBulkModifyCompatible(): bool
+    {
+        return true;
+    }
+
+}
\ No newline at end of file