How will ancestral property be divided

Hello sir v belong 2muslim.my father have 3bros and3sistrs (all younger)and one elder sis.my grand father purchased agri land in 1984 from others through sale deed before his death he mutated total land on my father name in 1994 through ror act in Mro office they have issued partition certificate on my father name through that certificate they have issued passbooks and entered in phahaani since that we are in occupation.after partition done my father younger brothers sold their share land to my father by writing on a normal rs 100 stamp paper.at the time of partition the Mro taken one declaration from my grandfather in that they wrote by agree of my other 3sons I am distributing total land to my elder son and on that paper my fathers other 3brothers also signed now after 20 years they(my fathers all brothers and sisters) filed a suit against us please let me know the opinion from you.