How to safeguard farmer's right on ancestor's land

Dear sir, my father is a farmer having two sons, and he has one elder brother who's a certral railway employee having a son. My father has some ansistor land and some purchased land during joint family and he relied fully on the farm land to feed my family. Due to family issues, now my grandfather and my uncle are trying to grab and sell the land. My father still relying on agriculture to feed family from past 40 years and he do not know any other job. where as my uncle being an employee he gets salary and pension too. Please help me how I can save my father's rights on land and counter the opposition fraud. Till end of joint family, for 30 years my father shared the crop yields and supported to my uncle family and to my grandparents. My father didn't received any amount or support in his life during crop loss or in draught or in expenditures or in children education. So help me in getting Justice to my father and right to have more share in land as our life depended on agricltr only