Cadence, Wow it certainly seems that Dad is in denial & clueless. (I was too, many years ago) If it were me, I think I'd just let it roll. Why would Dad even let him stay when already Jr is not living up to the rules, No Job?
If Jr is going to be in your life, I think it would be beneficial for both you & Dad to get to some Nar-Anon meetings. IMO