Stay against father in laws self aquired property

We have agricultural land of 3 acres. It was a self acquired land by my father. After his death it's now in my mother's name. Myself and my younger brother are the only two sons. Now my brother has applied for divorce and his wife had sent a notice by referring her 3 year's daughter. .that her daughter has the equal share in the property.so till she gets her share we can't suit schedule property in any manner, by creating any encumbrance, charge, mortgage, transfer, gift, sale. .. now what next we have to do. .. does she has any rights to claim against the property???