Land under posession - Adangal extract - petition not to give copy

Hello, The land owner sold the said land to us (to my grandpa) at 1975. However it is not registered, as there is a mortgage deed for 2000 rupees and the person is missing (or might have died). Since then, it id been under our possession, technically 49 years. My grandpa died and landowner also died We approached the heirs of the land owner to settle this thing to avoid complications in future, as we are ready to pay 2 Lakhs for late registration. Until we approached, the heirs did'nt know that a land exist, and gradually counter us that the land belong to them, we try to convince but they are adamant and asked to pay current market price (which is 50 lakhs). We filed a suit in district and local court. Lawyer is asking for attested Adangal document to prove possession. But the said owner(opposite party) gave a petition to VAO to not to give any copies to us. Actually we have retrieved current mortgage document, patta, chitta, A-register from internet. But TamilNadu have'nt start E-Adangal yet; Adangal has the information of the possession and type of farm done. Without this the case is not moving at all. It's been 6 months. Can any advise, is it possible to get the attested Adangal copies from RTI Act or by other means?