How to backup VM and ignore the pass-through disk?

I have a VM in Hyper-V with an OS VHD and a secondary pass-through disk.

Obviously, Hyper-V SS plug-in wont backup this VM because it looks like its an all or nothing deal.

Is there anyway where I can get avamar to backup the VHD of the OS without it caring about capturing the pass-through disk? 

I know altaro, and Microsoft Data Protection Manager can do this, I was hoping a Avamar could too.

Any suggestions?

Thank You