The dad needs to make the kid know this isn’t ok and get his rear end on the plane. Usually when a kid pulls this stunt, the other parent quietly makes it understood that it’s ok.
It makes them feel good to be the favorite.
A 15 year old boy needs his father.
She’s already made him go on tour with her, and even perform on stage with her.
Maybe the poor kid wants to be anonymous sometimes, and have a normal parent / kid relationship with his dad.
He’s at the age where he’s trying to figure out what manhood is all about.
Mom needs to grow up and let him go so that he can.