One of the first things that registerMember does is to check if $user_info['is_guest'] is empty or not.
If it is empty it redirectexit().
Why? Because if you are not a guest (i.e. empty($user_info['is_guest'])) then you are not supposed to register again.
So you can try:
global $user_info;
$user_info['is_guest'] = 1;
registerMember($regOptions, true);And if you have any way to know if it is really a guest or not, then use this check to populate $user_info['is_guest'].
