Whether Geft Deed could be conditional ?

After the death of my father in law, his three storied buildings were decreed for partition and my wife received one seventh of share. My wife would like to relinquish her right of one seventh of share or gift her share ( not yet partitioned by the court ) to her only brother with a condidition that her father's property / her share can not be sold/ transfered / gifted to any other her lifetime or atleast for next 5 years. Is this conditional relinquish of rights or gift is valid ? Is there any tax implecation in case no monetory transaction is involve ? Please advise.