Can Ex move in with boyfriend with my children?

Can my ex-wife move in with a man she is not married to, along with my 3 children? I’ve heard this is against the law in North Carolina and that she could lose custody of the children until either she marries the man or no longer lives with him in the house with my children. They are all under 18 years old.

Moving the children into the house of a boyfriend is not against the law. Unless there is a child custody order that directs where the children can or cannot reside, she is not in violation of anything.