Joint family property

dear sir, We are a joint family consisting of our father,mother and we are three sons to them, my father retired in 1996, my 1st elder brother started earning in 1989 and my 2md elder brother started earning in 1990 and myself started earning in 1993, what ever we three were earning we used to give it to our father and he used to pay part of our earning for taking a site on monthly installment, and my father bought 3 sites in Bangalore for us ( Registered 1 Site in my mothers name and 2 sites in our fathers name) during 2003, however as my father was having a affair with another lady and without our notice he has registered one site to the lady in 2006 and another he has registered to the ladies daughter in law. kindly guide me how we can take up the same in the court of law in 2017