what does the court order state exactly? If it says that this Christmas vacation is to be spent with you than your ex has no leg to stand on in court or outside of it. The court order will be what is enforced. He can however take you to court for a change in custody any time he decides to do so but the judge has to always look at what is in the best interest of the child and he'd also have to prove that there was a change in circumstances that would make it in the best interest of your child to be relocated to his home. Same goes for child support. He has to prove there was a change in circumstances to have it recalculated. Of course ever state differs.