I don't know of a blanket form for this, but she needs to know that regardless of what the parents sign, she will not be totally in the clear. It will help her if any issue does arise, but, in Ontario at least, people can not sign away their rights including the right to sue. Maybe she should see a lawyer. I'm sure it wouldn't cost much for a suitable form to be drafted up. A hundred bucks or so, I'd say.