Incorrect land record

My parents left some land about 1.538 hectares to their 9 children in Madhya Pradesh. After one of the heirs sold their share of land (0.17 hectares= 1.538 / 9), the rest of the heirs should be left with 1.368 hectares. But the online land records show the remaining land as 1.282 hectare which is around 0.086 hectares less (9000 sq feet less). Now other heirs are planning to sell their share of the land but no one is taking cognizance of this discrepancy of 0.086 hectares. If you take this 0.086 hectare into account, the remaining 8 heirs should get 0.16 hectare but they are applying for land ownership claim of 0.17 hectare in the court. As I am not planning to sell my land any time soon, I am worried that I will be left with very little land. There is hearing (in Tehsildar office) in December regarding this partition by the heirs to establish ownership. And I want that before any other heir gets their ownership to sell their land, we should have a professional land surveyor come to the property in question and take new, accurate measurements. And if the land is indeed 1.282 hectares then all the 8 heirs should get (1.282 /8 ) hectare. So, My question is what documents should I present in the court that might help me in this and do i need to hire a lawyer for this? and What should be the best course of action?