Add this friend to your XBL friends’s list: BRINK FoF
This FoF list will accept the first 100 friend requests that come in from BRINK players so you can use the Personal Profile > BRINK Fof’s Friends to find other BRINK players for 8 on 8 private matches.
From here you can message or invite any of those Gamertags.
http://live.xbox.com/en-US/MyXbox/Profile?GamerTag=BRINK%20FoF