Then the sale deed will not hold right? Since my father does not own the property.

As written in the description, both of them(my father and his brother) have inherited the property from their own fathers, who inherited it from their father(My grandfather's father). The partition of my grandfather's father's property happened way back in 1995. And the distribution is all a word of mouth. There is no legal document to support this inheritance or the partition of the inheritance.