disputed between father and son in ancestral property after death.

my grandfather ramesh purchasing a land of 246 square feet for making house .his eldest son murari also include his name in a registry paper of land against the favour of my grandfather ramesh in 1976.because murari uncle was a kanoongo at that time . but money spend for purchasing by ramesh.in 1988 murari uncle quarrel with grandfather and says that" in house 1/2 of mine ".grandfather request murari to convert registry paper only in favour of him because my grandfather having four son and two daughters. at that time grandfather suggested by lawyer for future secure for his children's. grandfather decided that he paid for murari in it .he paid 22000 of rupees in 1989 and bring by murari a written document in his handwriting with two witness and cancelled with tickket of 20 rs. and same date he prepare a WIll of house and divided between 4 son.and next date in 1989 grandfather prepare a notary by murari uncle .and in a notary affidavit murari uncle written that in above house I have no part of land for claim and I spend those money for purchasing i.e I get in from my father Mr. ramesh so in future me and my heirs claiming for that.he understanding declare to false.so from 1989 to 2017 murari uncle never quarrel for the land for 1/2 . he died in 2017.but in 2015 sita unadopted girl of murari ,apply undue force and emotionally, registered a WILL in favour of her.now the sita and her husband. wants to acquire 1/2 and more in that house and create daily quarrel. me and my family says to sita you are going to court and challenge for it.but she doesn't. hence sita is applicable for this challenge. because murari uncle doesn't claim in a court and never says after 1989 for it .sita born in 1992 and does not have a registerd adoption deed.plz help me and best suggestion to save our ancestral property