Notice Reply on Property dispute

In 1984 my dad has signed the document on 5 paper stamp and 3 person and dad brother in law had never signed the doc,stating that we would give 2 room against 10,000 rs (though it was not paid to my dad) taken for the purchase of land. In 1994 my dad and brother-in-laws again signed a new doc (signed by all the parties and witness) that all the properties(including the above property) that were purchased commonly will be distributed equally (properties that have the names of all or single or jointly owned) My uncle never gave our share on the property that was singly named on him inspite of above singed agreement(1994), a mutual and verbal agreement was done that he will not ask the share of properties where his name was not mentioned in the owner list unless he give our share on the property where his single name is mentioned as owner. My uncle passed away few years back now suddenly his sons and wife are calming for the share in the property based on agreement signed in 1984 but they are still not ready to give our as per the second agreement singed in 1994. Now they have sent the notice through the lawyer calming for the share of 2 rooms based on agreement 1984 no mention has been made of the agreement of 1994. Few are my queries 1.Is the agreement valid of 1984 after so many years as it was not registered. 2.can that document will be valid when the agreement signed by borrowing party only(dad) and not lending party (my uncle) and few witness. 3.Will first agreement is valid when 2nd agreement was made for the property that is being claimed 4.should we wait for the notice sent through court and then only reply to it.