1)on demise of your father you had 1/6th share in your father property
2) your brothers could not have sold father house without consent of the sisters .
3) if you had filed suit for setting aside sale deed and made brothers , builders party to the suit and stay was granted by court builder could not have demolished house and constructed building .
4) take out contempt of court proceedings against the builder .in the high court
5) also take out interim application in suit restraining builder from selling flats in building .
6) write to municipal corporation informing them of say granted by court and not to grant occupation certificate to the building constructed by builder