Not allowing to stay in ancestral property what to do

i have a grandfather's property in sitabuldi nagpur. My grandfather has 5 sons and 4 daughters. Property is undivided. all brothers except my dad where staying there. since we were financial sound we never bother of taking that as we were knowing and was tol by them whenever u require your part will be given to you. today when we are in need my parents went to them for having share in our property nobody was ready to give place in that property. one day they said dad to get out as we were not having any place so they fought and unlock the shop keys by stone which is under the same blg and started staying there. now since its a commercial area of 400 sqft with no washroom they had to face daily lots of problems and health issues. Todays we want our right in space people staying. They says jo jaha reh raha woh uski jagah. Now i feel like taking his extra space on 3rd floor which he made his bedroom even after having 3 bhk flat on 2nd floor, in the same way my dad has taken the shop.