If user chooses to change role after clicking special url, special url code is lost

I've got invite and rolesignup working together.

The problem occurs in that after the invitee receives an email to join. They click the special url with the code appended, see that they are being signed up for a specific role that they would like to change, click the link to change their role, select their new role, and get directed back to the form. Problem is, the code isn't appended anymore -- causing the inviter's invitation to still read 'pending' and breaking any functions such as awarding points/adding users to buddylists.

Is there a way to ensure that the special code remains appended to the url if a user chooses to switch their role? If I'm not making sense, I'll happily provide more information (and screenshots!)