Right of sister in law in father in laws property post husbands death

In 1969 my grand father had 4 sons, A,B,C,D, among the 4 of them 2 where elders and working in public sector company and other 2 minors were going to school, during this time the three working persons, father and 2 sons purchased land at 2 places , day went and the elder son (A) working expired, so the grand father manged the wife & 5 children of his elder son, later after 2 years the grand father expired, and the 4 brothers got split due to the maintenance problem of the deceased brother family, so the wife of the deceased brother started working for livelihood of there children, days after the three brother decide to divide the property , As the deceased wife (A) was uneducated the three brothers took advantage and divided the property as the 2nd brother (B) got higher portion and the the deceased wife and 2 brothers got equally portion, So now the eldest son of the deceased brother(A) feels injustice as the 2 brother (C) & (D) did not contribute anything for the purchase of the p