Validity of unregistered family settlement deed

I and my brother (who is not alive now) inherited agricultural land from our father. And both of us had 50-50% share in those agricultural lands. After my brother passed away in 2007, the names of his 6 heirs appeared on the revenue records of that agricultural land. My nephew recently took my signature in an affidavit, in which it was written that I relinquish 50% of my share of land to my nephew. I trusted my nephew and signed that affidavit without reading the details. Now my nephew has removed my name from the revenue record based on that affidavit. My nephew has not registered that affidavit. As soon as I found out that I have been cheated, I have filed a suit in the civil court regarding this matter. Our lawyer has stated in detail that the document cannot be accepted as evidence due to non-registration of the document. In response to the claim, the defendant's lawyer argues that since this is a family settlement, there is no need for registration. I have some questions in my mind regarding this whole incident which I am putting here with the hope of getting a suitable reply from you. (1) Can I legally transfer the right to my nephew? (2) Can such a matter be called Family Settlement? I request you to state your answers with supporting evidence i.e. act, section, judgment etc.. Thank and regards, Jagdish Patel (Gujarat)