Greetings. First, she should send him a letter explaining the negative impacts (keeping a copy for herself) and let him know that she plans to follow the custody schedule from this moment on. She should also talk to him about it, the best she can. If the child is not adjusting to school well, etc., both the parents may want to talk to the teacher together and see the school guidance counselor to see what they think.
Her ex may file a child custody claim based on the fact that his time with the child will now be limited more than it was before, but that will be unlikely if she slowly goes back to the custody schedule in the separation agreement and they make the transition gentle for both dad and child. Best of luck.
Janet L. Fritts
Attorney with Rosen Divorce
4101 Lake Boone Trail, Suite 500
Raleigh, North Carolina 27607
The response posted above is based upon the limited factual information made available and is not intended as a full and complete response to the question. The only reliable manner to obtain complete and adequate legal advice is to consult with an attorney, fully explain your situation, and allow the attorney sufficient opportunity to research the applicable law and facts required to render an accurate opinion. The basic information provided above is intended as a public service but a full discussion with an attorney should be undertaken before taking any action.