How to contest my grand father will show after 26 years of his de

Dear respected seniors, i need your help in a matter ...actually i have parental property from my grand father..my grand father was expired in 1989 and his 4 children one my father and remaining his daughters... disputes started when my father was expired on 18 october 2015...my grand mother & my bua's trying to escape me and my mother from parental house ...after so many problems i file civil suit in a court for justice in 8 jan 2016..parental house register in the name of my grand father till date in nagar nigam and i ensure no will make by my grandfather because he sudden expire due to heart attack.. now the problem is my grand mother and my so called bua's trying to register my parental house in his name during runnig of civil suit ..second, she shows will of my grand father i want to know simple important points to make a will invalid because shows in a court after 26 years expire of grand father in court 2) will type on a blank paper with the help of type writer ...whole matter typed but date is written by hand and place not mention and value of assests not mention ...so please give advice...