I stay in Pune City (Maharashtra State,India) . I have two sisters - elder sister stays in India and the younger sister stays in USA since 1987. My mother stays with me. Father expired in the year 1994.

In the year 1969 my father had purchased a residential plot in the area about 10 kms. from Pune city. There were 21 members in this society of plot holders. Father expired in 1994 and the share certificate was transferred in the name of my mother as per the nomination form given by father. Father had not made any Will. There was no development of the plot till 1996.

We all 21 plot holders approached a renowned builder for development of the total plot. The builder constructed big housing project of about 225 ownership flats in the year 1998 and gave each one of us (original plot holders) a 3 BHK flat free of cost. This flat is in the sole / single name of my mother. She has been renting this flat on leave and licence basis for the last 12 years.

My mother has nominated me and my wife in the nomination form of the society. She has also made a registered Will in the year 2003 in which she has mentioned that after her death this 3BHK flat should be transferred in the name of me and my wife.

My younger sister from USA has no interest in this house. However, my elder sister has started indicating her right / share in this property.

Can my elder sister claim her right in this property? Can the registered Will made by my mother be challenged after her demise on the objection that she was not the sole owner of this house and had no right to make such Will ? May I know the legal aspects of this issue?