My father's brother fooling us by taking our ancestral property worth crores.

Hello, I need urgent help from lawyers/advocate who can help me, I’m from lower middle class family and my father do small low wage work as a hawker and earn only 50k-80k yearly and he is a simple person, my father and brothers are three in total, my father is biggest one and middle brother who is fooling us and taking our part of the property share and small one is also simple business man who has already been fooled previously in property and again getting fooled, my grand grandfather was a property dealer/land lord so he owned so much land from which 18 acres is getting sold which is around 1800 dismil and total price around 2.34 crores as per paper agreement, my father’s middle brother made my father and small brother sign in stamp paper that he will give only 10-10% each to my father and small brother and keep 80% by himself and he is doing work through broker and selling the land and doing paper work etc, my father and small brother has already signed in stamp paper but till now land registry/selling has been not done and only agreement has been done and buyer has given 3 cheques of 2 lakh in each brother name, the land buyer is not knowing that my father and small brother is getting only 10% share so what to do now? please help my father to get atleast 25% share even if not equal, 10% is not justified and he is getting fooled and signed in force because my uncle gives pressure, my father is simple, we are lower middle class family and will pay lawyer/advocate fee after someone will help to get settle this and when we get our right share, this is lifetime opportunity for us, please help, I will show you stamp format which has been signed by my father with his Aadhar number, same format was typed and notary done in stamp, stamp paper is signed by my father and father’s small brother, I know that my middle uncle who is fooling hasn’t done much expenses or work and only hired some lawyer to do work, please help.