diff --git a/src/Entity/ProjectSystem/Project.php b/src/Entity/ProjectSystem/Project.php
index 0ffcbfe8..ce55b50a 100644
--- a/src/Entity/ProjectSystem/Project.php
+++ b/src/Entity/ProjectSystem/Project.php
@@ -116,6 +116,7 @@ class Project extends AbstractStructuralDBElement
     {
         parent::__construct();
         $this->bom_entries = new ArrayCollection();
+        $this->children = new ArrayCollection();
     }
 
     public function __clone()
diff --git a/src/Entity/UserSystem/Group.php b/src/Entity/UserSystem/Group.php
index d0af9f99..cb80ad39 100644
--- a/src/Entity/UserSystem/Group.php
+++ b/src/Entity/UserSystem/Group.php
@@ -97,6 +97,7 @@ class Group extends AbstractStructuralDBElement implements HasPermissionsInterfa
         parent::__construct();
         $this->permissions = new PermissionData();
         $this->users = new ArrayCollection();
+        $this->children = new ArrayCollection();
     }
 
     /**