Stamp duty on release deed

MHADA flat was registered in the name of my father-in-law. Through gift deed by father-in-law the flat go flat got transferred in name of my mother-in-law. During her lifetime she had made my wife (her daughter) the only nominee (without any will) of the said flat. Both, my father-in-law and my mother-in-law expired. On the basis of the valid nomination form, my wife's name was embossed on the share certificate. She has two younger brothers. All of them have 1/3rd equal undivided share in the property. We have now sold this flat. My does not want any share (monetary benefits) out of the sale proceeds. We are thinking of buying property in name of both my brother-in-laws alongwith my wife contributing to this purchase out of her 1/3rd share (to avoid capital gain tax). This will be held in joint names of my brother-in-law and my wife for a period of 3 years. What will be the income tax and stamp duty implications if my wife makes a release deed, of her share, in favour of the brother-in-law after 3 years ?