On grand parents demise your mother had one eight share in property standing in grandfather name
2) on mother demise her share would devolve on you and yiur siblings
3) issue legal notice to aunts for partition of property by metes and bounds
4) if they refuse file partition suit for division of property by metes and bounds
5) seek injunction restraining sale of property
6) you can take search in sub registrar office and obtain details of property standing in grand father name