How to regularize/legalize property documents

We have a property in Udupi, Karnataka purchased by my father in the year 1968. The property has 2 Survey nos.with Property 1 - 70 cents & Property 2 - 71 cents. We have constructed the house in 70 cents and adjoining to our land we were under the impression that the attached 71 cents is ours. But now, we have been informed that the 71 cents survey no. is not the adjoining one its after 2 plots. My father, when he bought he had planted 75 coconut trees and dug a well in the 71 cents which is adjoining to 1st property. Nobody has claim for this adjoining property but in RTC my grandfather's name is present and there is no other records other than RTC. The Property 2 which is after 2 plots is also empty and we have been informed by the village panchayat that it is our land as my father passed away in accident in 1973 and my mother unknowingly gave declaration to property 1 and property 2 as she didn't have any documents to claim the said property is hers and Government has granted these 2 property. Now, we don't know how to regularize the adjoining land which also measures 71.5 cents. Is there any law to acquire this land as we are holding this land and 10 years back we have dug one more well and levelled the entire land. Till now, its almost 50 years, no one have come forward and we are under the impression that this is our land and let us know how do we claim it.