Kidnapping / abduction / parental alienation?

Depends on the state laws, which vary from state to state. Also depends on the current custody arrangement. He should have legal documents outlining the restrictions. For example, mine says I can take my kids anywhere I want, but I am legally obligated to keep him informed their whereabouts and I have absolutely no legal right to forbid him to see the children. So he needs to read the documents, very detailed, and wouldn't hurt to allow you to do the same for a second pair of eyes. Also, he should probably be contacting a lawyer right about yesterday!! I know this is a financial burden, but perhaps he can find someone to help him "pro bono." Sorry to hear about such horrid parenting...not fair to the kids stuck in the middle of rash irresponsible choices.