modified activity streams in subdomain sites of multisite nw.

I have a multisite network using buddypress and your wonderful activity plus plugin. The site consists of a main sites and several regional subdomain sites. The main site displays a sitewide activity stream. I'd also like to display an activity stream on each subdomain, but with status updates limited to that regional site. I think I can do this by creating a group associated with that region? However, I'm not a coder, and can't figure out the activity stream loop coding that would allow me to limit (filter?) the stream to such group status updates. I figure it must be something using group_id. Any help you could give me with the coding/syntax would be much appreciated.