The Local Tribunal might have also delivered decisions on both perspectives as above…beased on facts, merits, irrefutable evidences
You may approach the concerned official that has record e.g; PA and ask for copies of previous judgments..
Approach senior LOCAL counsel of unshakable repute and integrity specializing in Civil matters and well versed with latest citations, LOCAL applicable rules/laws/ … and having successful track record…. and worth his/her salt…..and show the case related docs etc etc for guidance and help..so that you can present your version effectively.
The recourse of amicable settlement with Sr. Citizen Grandfather can be the best recourse..
Instead of losing the gift by order of authority ( if ordered in Tribunal, Appeals..)...
Rest is upto you.