Hey there
The BFM / guest xfire list was moved off the public forums. Was creating problems with too many names, people getting requests they didn't want but didn't want to say no to, etc. etc.
You can always pm anyone you'd like to add to your xfire... just keep in mind they may say no. Some have pretty strict guidelines from parents and such as to who they can add etc.
Or, you could apply, become a PR, earn your tags, and then you'd get added to the BFM xfire clanlist
One more bonus to being bfm/BFM!!
Just a thought