Can we determine share values and distribute them prior to parents’ demise?

I have a wife and 3 children. We live with my parents in one house. The house we live in is jointly owned by my father and mother, who happen to be married in community of property. I also have 2 sisters who are married and live in different cities. My parents have said that they want to give the house to me. As I understand the inheritance Shariah, my 2 sisters would have share in the house as well, and they are eager to comply with the Shariah. They are settled in their own homes and are very unlikely to come and live in this house. I suggested to my parents that we come to an agreement with my sisters for me to pay off an amount in lieu of their shares while my parents are still alive so I can plan for the future and make extensions to the existing house. I also suggested an agreement that I defer taking ownership of the house on my parents’ demise. (1) Is it possible to determine the share values of each inheritor prior to the demise of the parents? (2) If the above is possible can we proceed to distribute shares or to buy any individuals portion of the share prior to the demise of my father? (3) What is the Shariah status of the marriage in community of property of my parents and how does this impact on the distribution of the shares? (4) Is it possible that after the determination of the share values in the house (if this is allowed) to defer the actual transfer of the ownership of the house to myself when my parents pass on? Can such an agreement be put in place according to Shariah?