When a new user request comes in it requires a multi-step process to first approve the user, then go in and add any required groups, one at a time. There doesn't appear to be a way to add multiple groups for an existing user, that can only be done during a new user creation as far as I've been able to determine. Since the approval process is in fact creating a new user, it would be good if you could include the group memberships all in one place.