My grandfather had acquired a property (house) in the year 1956. He died in 1971 without leaving any will. He had 4 sons, all of whom are now expired as well. One of the sons (A) was not married and has no descendants while the other 3 (B, C, D) have legal heirs (sons and daughters, who are all married and have children). Now when we decided partition the property, one of the sons of B produced a will by A saying that A’s share in the above property will belong to him.
Is it legally valid for A to have willed his share in the property to someone else, keeping in mind that the property was a family-property (not self-acquired by A)?