Transfer of property

Background- The said property (a flat) in Pune, is on my mother’s name who passed away 5 years back. We are Catholic, Christians by religion. Now the class 1 legal heirs are her husband (that is our father) and her two daughters (that is my sister and me). 1. We now intend to have this property transferred on to my sister and my name under joint ownership. 2. My father has no issues in giving up his share on the property. 3. I would even after the property transfer on my sisters and my name would like to get some legal document made which states, my father would continue to live out his life in that said property and we daughters will not ask him to vacate or sell the said property in his lifetime, unless otherwise a wish is expressed by our father. 4. Can someone guide me through the best way of getting this done that will reduce any future paper work, even after the demise of my father or any one of us, the daughters. 5. We are looking for a financially inexpensive mode to have this done. Kindly advice all the steps involved, cost involved and time it would take. Thank you!