I also exposed the affair to my H's parents and hit a brick wall. I don't think it is that they don't have the moral authority it is that they just really can't be bothered with him or he is just not all that important to them, they think he is a screw up and this is just one more thing. They have not made any effort to contact him since, if he wasnts to talk to us he can come here. Sadly all it did was reinforce what H already thought about himself and give him one more obstacle in continuing in our R. I think this really works better when the person comes from a good caring family, but in your case her dad's behaviour likely formed part of hers and in mine his parents lack of support and affection likely formed part of his.
