My father two years back purchased a plot & suddendly came to that plot has already been sold one & that we purchased. after that my got cancelled that sale deed in registered office. & now we came to know that origional titile person selling the land to some other person. what are lagal conseqences. if that new person purchase the plot & came that he cheated. If he registered a case of Civil & criminal nature on that selling person, whether my father also become a party. please give come clues its urgent.