case "OnBeforeDocFormSave":
        $resources = array(
                $resource,
                $modx->getObject('modResource',$resource->get('parent'))
            );
        if($child_ids = $modx->getChildIds($resource->id,50,array('context' => $resource->context_key))){
            $resources = array_merge($resources, $modx->getCollection('modResource',array("id:IN" => $child_ids)));
        }