ExBIL was an emotionally abusive and controlling twat who SIL has finally managed to (mostly) get rid of. Ups and downs. He likes to threaten her and she hasn't quite mastered the art of realising that most of his threats are stupid and/or empty.
We have a plan is to go away in the summer with extended family. He is absolutely furious as one of his many weird issues is a complete inability to understand why he is not included in such activities any more. As a result, he has said he "won't allow" it and she can't take the DC out of the country without his permission.
I know for a fact that she doesn't need his active permission - I travel with the DC all the time and even with different surnames, it's never been a problem in Europe (I bring their birth certificates but only ever asked once).
But, in the unlikely event that he gets his ass into gear, can he contact passport control and put a flag on her leaving the country with their DC? I don't actually think he WOULD (he's lazy and pathetic), but can he?