Create Session Group that filters other Session Groups

What I mean by that is the following. I want a Session Group that specifically contains all Guest Machines that belong to a user.

I have a Session Group called "All US Machines by OS" and a Session group called "US Servers".

I would like to create a SG that simply displays everything from the former, excluding all from the latter.

I thought I'd be able to do something like this with NOT $OTHEROR but I'm having trouble working out how that variable functions.

I'd also add a clause for [AND name NOT like "*test*"], but that should be simple enough once I figure out the first part.