is update approved for specific group via powershell?

Hello, 

I have a script that auto approves updates based on release date for specific groups. The script checks to see if the update has already been approved (e.g. isApproved) and either skips it if it's already been approved or approves it for my specific group (e.g. $update.approve("install",$wsus_group)). The problem I'm running into is if I approve Update1 for GroupA, then later check Update1's isApproved to see whether or not I need to approve it for GroupB, Update1's isApproved is $true and therefor my script skips approving it for GroupB. I've checked the update's object and I don't see a multi-valued var for groups that its been approved for. I've started to poke around with other Microsoft.UpdateServices.Administration namespaces but I don't see one that has the info I'm looking for. 

So, how can I view what updates have been approved for GroupA vs GroupB?

Thanks!