I think it would be a better idea to take the fresh poo from your house and carry it outside to your yard with your dad's dog and show him where his poo is supposed to go. You may also want to give him a treat after he sniffs his own poo so he can relate something good to his poo being outside.
Then, next time it's time for him to "go" - take him to that spot and let him smell his poo again so he gets the idea. And, by all means - even if you have to be out there all night - don't let him back in until he eliminates. Then, give him goodies again.
I know it's frustrating and time consuming but it's better than poo in the house.
Also, make sure you are cleaning the spots in your house where he has pooed before really well - with bleach if it's hard floors and with some kind of enzyme solution if it's carpet - so he's not resmelling his old deposits there.