Sister claiming property bought by father in name of minor son

A house was bought by father with the self acquired income under his son's name when he was a minor. When son started working, he extended the old house and built 1st floor. Father died without a will in 1999. He left behind lot of debts in many lakhs and a unmarried sister. Son duly paid off all the debts with interest, married off his sister and took care of mother and her medical treatments. After son settled all the debts and mother passed away, sisters want to claim for the house which father bought when he was a minor. Do they have rights to claim that property stating that it was bought when brother was a minor with no income and that father did not leave any will. Note: Father sold another house which he received from his father during the partition to spend for his first daughter's wedding.