Dynamic Group - Temp Membership

Hi Team. 

Just looking for some suggestions or ideas. We use Dynamic groups based on a VA being set. Our Service Desk select this from the WI. 

We have a couple of Dynamic groups where we want the membership to be removed after 48 hours after the account was added to the group. Now i know i could use a standard group and use the temp membership route but we then loose the ability of our Service Desk team just ticking a box. 

So what i was thinking was that i could have a script that checks the group every few hours and then set the VA back to false. But is there any attribute that tracks when the user was added? or is there a way i could add a time stamp attribute?

Open to other suggestions or ideas?