Me and husband want to buy his dads flat?

we are trying to look into best way to do this my husband can either go on the the morgage which has 26 grand left we pay off the rest then fter his dad has found somewhere rent it out, or he can sell the flat to my husband for what ever he asks for and he lives there for a while then we rent it out, me and my husband already pay rent on our home his dad lives in this flat he needs a council bungalow so we are trying to find away we can keep it and he gets his home he needs as it would be past to his son anyway his dad was going to sell it to us for 26 thousand as thats whats owed on the morgage then he pays off his morgage and he wilo get council place and wont lose benefits as he wont have made no money hs anyone brought a home from family