The only thing I can think of after looking at the api could be adding the groups names to the players friend list then use GetFriendInfo(index). Only problem I see with this is you would need to query for the number of friends GetNumFriends() then loop for index matches by checking the name returned GetFriendInfo(index). I do not know if the indexes change as users sign on, I would assume they don't meaning once you grab the index just a matter of querying the players that are offline until you get an online response. Kinda sounds cumbersome to me but I can't think of any way for members to discover members.