XF 1.5 Custom User Groups


Question: is there an add-on or a way to automatically add users to specific user groups?

On my forum, we have a group that is called "inactive" so is there a way to have users added to that group automatically if they haven't logged on for 6 or more months? It just seems like a chore (and I'd forget) to go in and do it manually by batch update every month or so.