[Yellow Slider]

You can do something like this:

PHP Code:

$paid_members_ugid = 10;
$userdm =& datamanager_init('User', $vbulletin, ERRTYPE_SILENT);
$userdm->set_existing($userinfo);
$userdata->set('membergroupids', ($userinfo['membergroupids'] ? implode(", ", array_push(explode(", ", $userinfo['membergroupids']), $paid_members_ugid)) : $paid_members_ugid));
$userdm->save; 


Haven't tested it, but it's supposed to work.