Threat to mine father to vacate house from his elder brothers

Mine Taujis who are US Citizens after staying and working in USA for almost 40 years are forcing mine father to sell the ancestor house, they are still residing in US and visit India sometimes in a year. Mine father stayed in this ancestor house along with mine grandparents to take care of them and staying here since 40 years. This house was constructed by mine father while mine Taujis were in US , they moved to US at a very young age of 20's. Mine Eldest Tauji threatens mine father over WhatsApp call from US to immediately sell the house or mine father will face the consequences, he has warned mine father to immediately vacate the house and hand over the keys to him once he visits India this year and we to shift in rented house till then unless this house is sold and amount is received which will be equally shared among the 3 brothers, out of respect and fear mine father who is youngest among brothers is agreeing to do so but he is also worried and emotionally broken to leave the ancestor house and resettle elsewhere his age is 70 years. There will be extra Burden of rent for us in that case and no one knows when the house will be sold. To add on to this There is a will created by mine grandfather including names of mine two taujis and mine father. The will is not in registered state. Mine father also runs a small consultancy from home to meet the ends. I have suggested mine father to file a partition litigation but mine father is worried and afraid. Mine taujis are forcing mine father to sell the house but I have suggested him to file partition and divide the land into 3 parts and do the re-construction on the 1/3 land. Mine sister is in final year of college and the hostile environment of threats to mine father from mine taujis is also disturbing her studies. I am suffering from an auto immune disease and mine condition has limit mine movements. I also have 3 buas (father's sisters) but they are not part of the will. Please suggest here.