Filter by IP address in GSS?

I am wondering if there is a way to filter the Default machine group in a way that would seperate machines by office location. We have 5 offices across the US and I would like a dynamic group for each of them. I have tried a few different filter settings such as clicking IPAddress under Network Adapter Configuration and inputing "10.10." for the string and can't seem to get machines to show based on IP address. Each office has a separate "10." address ranging from "10.10." to "10.50." so this would seem to be the way to go. Does anyone have any ideas? I was going to resort to using the user's timezone as a filter but two of our offices are in the same timezone.