before_relationship_delete related module id

in before_relationship_delete how can i get related module id ?

i tried 

function before_relationship_delete_method($bean, $event, $arguments)
  {
    $GLOBALS['log']->fatal(' 13 ' . $arguments->module);
    $GLOBALS['log']->fatal(' 13 ' . $arguments->related_id);
    $GLOBALS['log']->fatal(' 13 ' . $arguments->related_module);
    $GLOBALS['log']->fatal(' 13 ' . $arguments->link);
    $GLOBALS['log']->fatal(' 13 ' . $bean->id);
    $GLOBALS['log']->fatal(' 13 ' . $arguments->relationship);
}
in parent module , but all of these value is blank , i also tried in child module , where can i get related child module info