Since the lawsuit has reached the evidence stage, this is the most critical phase of the trial  in a civil property dispute under Hindu law,

Under Hindu law (even prior to the Hindu Adoptions and Maintenance Act of 1956, under old customary Hindu law), a validly adopted son steps completely into the shoes of a natural-born son. If your FIL's father was legally adopted by the grandmother, he and his lineage (your FIL and now your spouse/MIL) have an absolute right to a share in the ancestral or grandmother's property. Your evidence must firmly establish this adoption.

Under Section 17 of the Indian Registration Act, 1908, any transfer or gift of immovable property must be registered to be legally valid. The fact that these 1965–1975 transactions are handwritten and unregistered is a massive weak point for the uncles.

The uncles' primary defense will likely be that the transactions happened 50 years ago, arguing it is too late to challenge them. However, under Indian law, if a property transfer is based on active fraud and concealment, the clock for the time limit (limitation period) only starts ticking from the date the fraud was discovered. Your family needs to firmly establish via evidence that your FIL had zero knowledge until he pulled the RTC printout five years ago.

Whoever is stepping into the witness box needs to be  familiar with the timeline. They must remain calm during cross-examination and consistently stick to the truth: The uncles hid the documents, the documents were never registered, and the family only found out through the RTC.

Once the evidence stage concludes, the court will hear final arguments from both lawyers and then deliver its judgment.

Gift deed has to be stamped and registered to confer clear and marketable title to property 

un registered document is not admissible in evidence 

Your mother in law has to take the plea that father in law had equal share in the property  and gift deed is not valid 

In evidence stage, both the parties have to prove their contention by producing documents. 

In evidence the plaintiff will try to prove his case and defendant will falsify by cross examination 

Dear Sir/Madam,

At the evidence stage, your MIL and sons must file affidavits, produce original/certified property records and witnesses, and face cross-examination. Thereafter, the defendants will lead their evidence.

Your lawyer should summon the old revenue and registration records and prove the alleged fraud and late discovery. An unregistered document purporting to gift immovable property generally cannot legally transfer title.

Advocate Saurabh Agrawal