What is your query?

Deed of relinquishment has to be executed duly stamped and registered 

mete affdavit by siblings does not result in relinquishment of property 

Then such right can be relinquished

This affidavit has value in the eye of law.

Te right of a person over an immovable property can only be obliterated by a registered deed of conveyance.

So the siblings can relinquish their respective undivided share in the joint property by way of a registered deed of gift or deed of release.

Such relinquishment can not be done by an affidavit.

The affidavit is valid and can be used in judicial proceedings though kindly clarify your question.

What is your query?

You have just written the fact 

Kindly elaborate 

Regards 

It would be better for you to take proper legal guidelines by showing complete files of your case to an advocate so that you can take a right path to handle your issues.

An affidavit  for relinquishing the rights is not valid in law, it has to be registered document.

A judicial magistrate cannot authenticate this document even if does,m it is not valid since the procedure for this is to be executed by a registered document only.

Judicial observation and recording same in order is absolute.

1. As per the information mentioned in the present query, makes it clear that you want to know the legality of the affidavit, as per I am able to understand.
2. Yes, the affidavit would have all legal validity as the same has been executed before the JM.
3. But, there must be a relinquishment deed along with the affidavit to show that siblings have actually rendered their right in the ancestral property, which might be missing as per the above information.