I can''t offer any words of advice, I find it amazing how far parents will go to use children as a weapon. He may think he has ''won'' but really what has he won? He has prevented his children having a holiday....nice one. Sadly one day the kids will become aware what a d!ck he has been.
I have the opposite issue in that my eldest child doesn''t want to go on holiday with his mother to his grandparents in the EU, for the last 2 years I''ve had to tell him ''you are going, suck it up''. He would be welcome to stay, but my ex wants him to go and I think he should go to see his grandparents.