If you have the same ACBL number associated with 2 or more BBO handles, could BBO not discover this behaviour? I suppose you could play a daylong a couple of times with a handle with NO ACBL number, then play it with your regular username that does have your ACBL number associated. That would certainly give you a leg up on some board, but not all. Surely this could also be tracked, though, just by virtue of the fact that you are getting too many excellent boards for your skill level. It would be weird for players with no ACBL number to play these games since they are much more expensive than the ones that just offer BBO points. Bridge players have to think like a detective, so I still think they would get caught eventually.