Thing is, this has always been an "exploit" of wings / multicrew. If somebody hires me to mow their lawn for $20 and I bring a friend to help me out, I'm going to have to take a cut out of that $20 to pay him. The guy with the lawn isn't going to hand out extra cash for every helper I bring. Yet this is exactly how multicrew / wings work. I'd be totally fine if proceeds were divided among my crew rather than multiplied, but I'm sure somebody would complain about that...
sent you a friend request in game if you would like to test the multicrew interaction out in various situations between fc/stations. Then we can find the actual situation and where the issues lie. ignore it if you would rather not.