Selling of ancestral property by grandmother

After my death of my grandfather whole rights of ancestral property came to my grandmother. Recently my grandmother equally partitioned the land and gave to all their 6 children 2 sons and 4 daughters. She got the remaining small land with the house for her living. Initially it was planned like whoever looks after grandmother among 6 children can have the house. But there was no agreement just a mutual understanding among children. One of aunt thought of looking after her but she didn't look after her properly and left her alone and went. Before my aunt left from there she has asked for small land from her grandmother for making way to her land. So aunt exchanged some land from grandmother which we didn't come to know. Aunt has made agreement too for that land. After that she left grandmother alone at home and went. After some days my grandmother was not able to look after the house and she thought of selling the house. So grandmother asked to my mother first as she is elder of all. So my mother got the land and house for ready cash and made agreement. After we got it we came to know that there was lack in the land size when measured which was written in agreement. We asked our grandmother to recover and she told the whole story of what happened. My aunt had put fence taking some land from my grandother unknowingly. So when we asked directly to aunt to measure the land they are not allowing us. So we thought of giving petition to sub collector for recover our land lost. But collector gave us result as it is civil case which cannot judged here. What should I do to recover our land which is aunt's land.