Here's how you do it right now, without any kind of mods to your User Control Panel.
If you choose "FRC as your competition, it will display
FRC #xxxx (team name) in your profile, but you can make it display
FRC #xxxx (team name), FVC #xxxx (team name), FLL #xxxx (team name) or any other combination of these if you want. All you need to do if go to the "Team Name" box, and type in the following:
team name), FVC #xxxx (team name
or
team name), FVC #xxxx (team name), FLL #xxxx(team name
All you need to do if replace the first "team name" with your FRC team name, the "#xxxx" with your FLL/FVC team number, and the second "team name" with the name of your FLL/FVC team, and so on. Do not add a closing parenthesis after the last team name, as it will show up as having two parenthesis' in your profile on your posts.