Ancestral land - tax paid by another person

My grandfather had a property(passed away in 1978) which he had owned and my father was not aware of it. We have the original documents with us that we own the land with the old survey number. We somehow got a guy from the village office who was ready to locate the land for us and he got us the new survey number as a re-survey had taken place in 1994. We got the re survey number along with the plot sketch with the Superintendents sign from the collectors office in our district. Our next step was to pay the tax for the land as we had not payed it from 1978 since our grandfather passed away. The guy with us went to the village office with the new survey number and we came to know someone else paid the land tax from 2007. Our guy said the BTR(Basic Tax Register) is in my Grandfathers name but the Thandaper is in that persons name who paid the tax. (I dont know to explain Thandaper which is a malayalam word i guess - i think the guy who paid the tax last will be in the tax register or something ). I also had an advocate helping me out for all these and he told since we have the original docs and the BTR is in our name we will get the property So he send 2 letters with RTI to the collectorate office and one to the village office seeking the details again with Correlation statement, the BTR , Thandaper,the details of the fraudster, the plot sketch and all the details. We send it today that is Aug 9 and hopefully will get a reply. My question since we have the original documents and the BTR is in our name, will we be able to get the property back since the guy started paying tax only from 2007.? Also how are these people able to pay the tax when the property is not in their name? Is it with political influence? or did he get some help from the village officer or the Superintendent to pay the tax ? Even if he makes a fake property document . Is it valid ? The advocate told me once we get all the details we can file a complaint with the vigilance against the person,if they are not ready for an out of court settlement and the last option would be to go for the civil case ? I just wanted to know whether we will get the property.?? Hoping for a reply from experts