Forcefully staying in our property

Sir, We are three sister and our mother has passed away in 1970. She was having one property in her name which is self earned property. After her death recently in 2015 our father who is also aged has given the release deed on all the three sister and we have transferred the property in our name. Our father has one more marriage after our mother's death. Now our step mother is staying in that house forcefully and she is not vacating the house. This is also to inform you that our father has one more property in his own name and that is self earned property by our father. That property is all controlled by our step mother childrens and the property which was on our mother's name and which we have got transferred on our name is also forcefully occupied by our step mother and their children. What is the possibility of vacating the property which is in our name from them. Our step mother and their children is not taking care of our father too. So our father is staying with us. Kindly help us in guiding the legal procedure and how can we get the vacation of the property which is in our name.