Property

My mother property I.e agricultural land was sold by my mother and sisters during registration day called from registeration office asked me and elder brothers. Since property was sold by mother. All brother did not involved and signed the papers. Later got know that my younger sister did signed. Now she is files case against all brothers and sisters saying she did got the share. I have not taken single pie from that. I do agree and support my sister due to she is financially sick due her husband not earning and not doing any work. Another problem is during negotation of price etc., my close ralative misguided my mother and sisters and paid Rs. 7lakh for 8crore properties. How can win the case and how fast can.