Can father in law transfer a property to daughter in law.

Hi sir. In my sister family there is a property transfer doubt. Father in law is ready to transfer one of the properties to daughter in law. His mother is written WILL for that property as "this property goes to my son, if he is not used(sale, settlement) it goes to my grand son)". But he wants to transfer this property to daughter in law instead of son. Which option is better and how much amount need for transfer this property to his daughter in law. If settlement means how much amount we have to pay for registration and stamp duty.