Originally Posted by
behuman
It's a risky game, possibly fraud and certainly against the terms and conditions of your FFP which could lead to you being excluded from it loosing the accumulated miles on the way.
Would not risk it.
I haven't seen or heard any T&C about you are only allowed in 1 lounge, and it will be difficult to restrict people can only use 1 lounge, as not all lounges are built with the same amenities even within the same airline in the same airport. The only rule is 1 guest only, so as long as you bring A guest to A lounge, B guest to B lounge, you are totally fine with it and totally within the game rule.
The only thing is I wouldn't attempt to bring both A and B guest into the same lounge.