I have done a CSV import for something else before, so I could do that. Only problem is that I would need to manually keep the group up-to-date. As for the rule to Add values to a user defined group, the rule would still need to be able to identify who admins are. I find it troubling that when looking in the Windows logs it doesn't identify admin users as admins.
Thanks for your help on this, I'm going to contact Microsoft and see if there is something I'm missing with the logs or if we have something configured wrong with server logging.