I understand your connection to poor guy but he needs to get organized and move on with his own ambitions.lodging with you is going to repress his progress. I'd make it very clear that he's always welcome to visit and that he has our friendship always of that's the case , after all he's your GK father and if he's done no wrong deserves respect and consideration .having said that, go no further, your DD is doing what many do after hitching up very young , I did same, had my youth in my 30s if you like, once I split from an unfaithful selfish spouse. Stay friends .