$gm = DB_Dataobject::factory('core_group_member');
$gm->group_id = $this->id;
$gm->user_id = is_object($person) ? $person->id : $person;
$gm = DB_Dataobject::factory('core_group_member');
$gm->group_id = $this->id;
$gm->user_id = is_object($person) ? $person->id : $person;