just an idea combine quick claim deed and seller finance.
RE: deed - Your father signs the deed over to you. You record the quick claim deed at the court house. The deed to the property in now in your name. You then have legal ownership.
RE: mortgage / purchase price. Your father keeps his mortgage and you make the monthly payments to the bank to pay off his loan. The bank does not care who makes the payments. The bank just cares that the payments are made.
If you are buying the house for more than the balance on the mortgage loan, your father creates a note (an I owe you). Do not record the note. You can then ...
1) Pay off father's mortgage first by making monthly payments, then get a bank loan to give father his remaining balance.
2) or Pay off father's mortgage first by making monthly payments, then continue to make monthly payments your father. AFTER your father's mortgage is payed off, You/He can record the note .