Petitioner claim despite dependent clear title and possession

I have an inherited agriculture land property in Kotdwar, Uttrakhand,having clear title and possession since 2001. The patta of the property was given to my grandfather by Kham Supdt. during Britishers time in 1928.On death of my grandfather in 1947, it was transferred to my father's name in 1948. In 1976, he had been given bhoomidhari rights after depositing 20 times of laggan and certificate issued to my father by Dy. Commissioner. After father's death in 2001,mutation was done to me and my brother name. We have clear title and lagaan receipts even to my grandfather's name for year 1932.We have clear khatauni in our name. 30% of property had already been sold out by my father, myself and my brother.My brother is also expired in 2011 and now his hare has been transferred to his son. Now , one COUSIN to my father, claims that he is the joint holder of property and claims that instead of my grandfather , it was owned by my great grand father. He has filed a suit u/s 229 B, in SDM court in 2013. He claimed that he should get the share as the property was not to my grand afther but to my great grand father. Now, after 3 years, it has reached in cross examination stage.Petitioner has not submitted any document except narrating the family tree and reference with some remote village property of my great grand father that alonwith that property, this property is also a joint property. From RTI sources, he got letter that there are no records available in Revenue offices.he stated that my father, me and my brother had destroyed all the records in Revenue offices etc. However, I have the original Patta to the name of my grandfather and Lagaan receipts of 1932/34 to my grandfather issued by then patwari. I maintain Khatauni records and check that no fraudulent name finds any entry. I have hired a local lawyer and so far shown the Bhumidhari certificate to my father of 1976.The other party or his father/ his grandfather have neither any title nor any possession physical or in legal records so far.Now the petitioner's son in law has taken POA and fighting case on his behalf. They have not submitted any document for property title or possession so far. During cross examination,the POA had wrongly stated that his principal has the possession but he does not know where. He has no house at Kotdwara. He does not have any document except RTI references that no records are available in the Revenue offices,etc. I shall be grateful if you could advise the course of action and (i) whether the case is barred from Law of LImitation Sec 65; (ii) whether under Order 3 Sec 1 & 2, this POA can give witness on principal behalf when he does not have personal Knowledge (He stated that he knows the principal from 1988). (iii) Whether the POA valid. His lawyer is from Nagina UP, he made POA on stamps from UP got signed in Jodhpur Rajasthan where pettioner stays. (iv) whether burden of proof is not the responsibility of petitioner. Should I make the reference of my original Patta to my grandfather. I have apprehension that I may be required to deposit it as priimary evidence which should not later get misplaced as I am not confident the way these local courts operate. Now, I have my cross examination on 10th August and request if you could kindly advise me on the subject, please. Thanks & Regards