Affidavit notarized for family settlement on 100 bond paper

My son expired intestate married with no kids. My son owns 3.5 acres of land in village. My self and widow (daughter in law) mutually agreed to transfer 3 acres of land owned by her husband to me so that equivalent value house registered on my wife name will be transferred to her as mutual understanding. We agreed and signed an affidavit (notary) on 100 rupees bond paper and signed + (LTI of both parties) and sealed by notary infront of other two witnesses. In same affidavit we mentioned in future she (widow) should not come back and claim rights on other properties owned by family members acquired or ancestral. My question will this Affidavit(Notary) valid as agreement or is there any expiry to this affidavit what we agreed to?. 1. Do we need go for new settlement of deed agreement and register it in registrar office by paying value of the asset ?. 2. Is there any expiry or invalid concept after certain period for affidavit which we executed already ? 3. As you know we cannot register affidavit(notary) in registrar office? 4. Can we use settlement of deed for our mutual transfer of properties?. Please advise here how to legally close this family property settlement to transfer land and house between both parties. We need to avoid future litigation's for next generations on other ancestral and self acquired properties.