implementation of role escalation for already registered users

I am in need of the invite module to not only escalate user roles for newly registered users, but also for existing users.

Basically, there needs to be a way in the admin panel to disable the "filter out registered users" function so that the email still goes out. So, instead of receiving the error message saying the user already exists and not sending out the email to that email address, it should still send out the email and only alert the user that the email address is already registered to an account. It's nasty, but for now, I simply commented out: $failed_emails = _invite_validate_emails("SELECT mail AS email FROM {users} WHERE mail IN (%s)", $emails);

Then, when the invited person clicks on the [join-link] in the email, whether they're logged in or not, it needs to check to see if that recipient's email is associated with a user account in the database. If it isn't -> registration page and escalation after registration / invite stats updated. If it is and they're not logged in -> login page and escalation after login / invite stats updated. If it is and they are logged in ->escalation / invite stats updated.

What'd be even nicer, is if you could configure a custom page redirection for all three scenarios. But that could come later down the road and can even be partially dealt with through another available Drupal module.