Living will question

So we have 2 kids and are planning to get a will stating who would get our kids if something happened to us. We have already spoken with these people and they agree. My husband and I don't speak to his side of the family. Is there a way to put in a will that under no circumstances should my kids be given or forced to have a relationship with his side of the family? His dad is a narcissistic alcoholic and that's just the surface. I want to ensure my kids are safe legally If something we're to happen.