Gpa validity

GPA automatically cancelled  and not enforceable on the moment of principal's  death.consent/NOC obtained by principal's legal heirs has no value and does not validiate GPA.

Whether it was irrevocable GPA against value of property?

Under specific relief Act, file a Civil suit for cancellation of document.

The General Power of Attorney (GPA) executed by your grandfather in 1996 would typically become void upon his death in 1997, rendering any property transactions made by the GPA holder in 1999 invalid. Since the GPA ceased to be legally effective after your grandfather's death, the transfer or sale of the property would not hold legal ground. Additionally, if your father and uncles were coerced into giving a No Objection Certificate (NOC) without their genuine consent, this could further invalidate the transaction. You may have grounds to reclaim the property through legal action, challenging both the validity of the property transfer and the NOC obtained under duress. Consulting a property lawyer for tailored legal advice and considering a civil suit to assert your rights would be advisable.

Thank you very much to all who have replied to my query. Thanks sir.

No conveyance of immovable property can conferred title on any immovable property by Will or Power of Attorney. Thus, in absence of Deed of Conveyance the GPA will just be a mere piece of paper.