You got excellent advice from my two favourite more resourceful people, Wylie's Mom and Maximo.
I think at this point, most importantly is to prevent accidents. That way, your puppy will learn faster and your dad will be less frustrated. To prevent accidents, as Maximo suggested, keep him in an xpen (or a small isolated area without carpets) with a potty pad. The smaller the area the better, so the puppy is able to get to the pad when he needs to go. When they're young, they can't hold it and when they gotta go, they just go wherever they're standing.
I highly suggest getting him used to a potty schedule. So that he's in the xpen/isolated area during his potty breaks. And only after he's gone, do you let him out for some playtime. When it's near his potty time again, within one or two hours, keep him with you in your lap and not on the floor. And for now, definitely don't give him free access of your entire house. Make it a very very very slow transition to gain access of your house.
Basically, with each week he is accident free, you can give him a little more access. Once he has an accident, revert back a step. It takes a lot of patience. But with time, he'll learn! Make sure that every time you see him potty on the pad to celebrate with a "good boy Ricki!!!!!". They love to please and love compliments.
About the difficulties with family members interferring - that's a tough one. I can totally understand. My soon-to-be in-laws had a lot of comments, as if they were professional dog trainers (but they're obviously not). They basically asked each day, "isn't he potty trained yet?" within a month of me getting Scottie. It was a pain. Luckily I don't live with them.
I had to pretty much tune out their comments and just focus on what I knew to be the right thing to do. Doesn't really help for your case with your dad though. But I do think that if you're able to prevent the accidents, it should definitely help.
Keep us posted on any progress!
