Distribution of fathers property among sons and married daughter

Hello, My father had his own property at Mumbai. He had 3 son and one daughter, all married. 2 son after marriage got separated and lived in their own house. Daughter also married. after fathers death mother used to live with all the sons (3 months with 1st son, next 3 months with 2 nd son , next 3 months 3 son and then with daughter). Mother also died few year back. Now 1st son is staying in the house owned by father (since last 20-25 yrs) with his wife and a married daughter and son in law. Now rest of the siblings want to sell the property n distribute the money equally among themselves. Now the son staying in that house says that he is old and cannot leave the home, he is not earning now and dependent on daughter and son in law financially. Rest of the sibling r trying to make him understand that after selling the property he can purchase a small flat in outskirts and his daughter can send him monthly expense as the outskirts are not far from Mumbai. Property market value is more than 70 Lakhs, (MHADA construction). But the son and his wife are not ready to leave the house saying they are old n not earning. Rest of the siblings are not financially strong enough to go under legal process. Will is not written by father neither by mother. What can be done in such case.