[Paul M]

The only way to remove the limitation is to remove the check in memberlist.php ;

This is the code you would need to remove ;

		// check permission to do authorizations in this group
		if (!$leadergroup = $db->query_first_slave("
			SELECT usergroupleader.usergroupleaderid, usergroup.title
			FROM " . TABLE_PREFIX . "usergroupleader AS usergroupleader
			LEFT JOIN " . TABLE_PREFIX . "usergroup AS usergroup ON (usergroupleader.usergroupid = usergroup.usergroupid)
			WHERE usergroupleader.userid = " . $vbulletin->userinfo['userid'] . "
				AND usergroupleader.usergroupid = $usergroupid
		"))
		{
			print_no_permission();
		}