I would expect these wings to be just like any other wings with players. Max 4 in a wing, so you cannot wing up with your friends if you are already in a full wing.
If 4 players thinks it is a good idea to fly in their own NPCs wings, I see no problems with that. There can already today we several separate player wings in a system/location.
There's something called anchoring in the game. It's something ppl do to get more than 4 ppl in a fight.