father passed away intestate and property distribution

Dear Sir, My mother is a 70 year old widow and my father passed away with out leaving a will. Apart from my mother we are three children, 2 boys and a girl. My father passes away in 1997 and left behind a self acquired property. ie., 60*40 two story house in a posh area in Bangalore. Later in the year 2009, we changed the house khatta to mother's name as we built another floor on the existing house. Now as far as my understanding goes all four of us ie., mother and 3 children are equal share holders in the property. But now the problem is that 3 out of this 4 want to sell the property and share the money equally but the elder son is not agreeing to it since he'll lose out a share of mother's property and he is waiting for her die so that he can stake a claim in her share of the house. So, what can be done about this? Else, our mother feels that she wants to gift deed her share of the property ONLY TO HER DAUGHTER. So is that possible since it is not her self acquired property? Or should she make a Sale deed instead of a Gift deed? Or should she just make a "will" on how her share should be distributed? Kindly answer as I am really looking for an expert opinion.