Adding a user to the IDV 'ONLY' when membe of groupX

Trying to add a user to the IDV only when they are a part of groupX. This is a AD driver 3.6.1, the group modify and user add is on the publisher side. Ideas? So, thinking I am going to have to take the modify group - member add event - and then do an 'if' on all the member to see if they exist in the IDV. If not, generate a user add event.......Am I making this too hard? Any ideas?

Thanks in advance.