liability of legal heir

Yes.   Please go amicable settlement. Otherwise, file a declaration suit.

What are the facts? What is the context?

If the legal heirs refuse to execute the registered rectification deed to rectify the error in the registered sale deed, then you can file a suit for specific relief against them after which you can proceed legally on all such further issues as per procedures of law. 

To my understanding, particulars as to share certificates (in the Housing Society) is not substantial to the rights that has been conveyed to you through registration. As such, there is no need to wake up the trivial issue unless the discrepency has resulted in any inconvenience or impediment.

Agree with Mr. P. Venu

What is the inconvenience? Who has raised the objection

Anyhow, it is impossible that there could be a timely resolution if the civil remedy is sought through a suit for specific relief.

The querist is not able to express his actual problems, and he is giving piece meal information which do not make any meaning.

He is mentioning about the share certificate at one place and the legal heirs of the deceased seller, but now he is mentioning that the owner is facing inconvenience to sell this property, now which is true and what is the actual problem.

No doubt the share certificate is not a title document but his problem is something else which he is not even understanding.

The querist is just jumping into this forum frequently  with some questions without even knowing whether the questions carries any legal sense or not.

Unless and until he is not explaining the actual problems he face, no opinion can come to his rescue hence it would be better that he consult a local lawyer and try to find a solution

If the rectification is not carried out then the title to the seller is defective therefore it is natural that the buyer would not be willing to purchase the property with defective title. 

The newspaper publication is not the remedy. 

The seller has to comply with the legal necessity if he wants to sell the property. 

The seller cannot think of fraudulently selling the property. 

You are yet to disclose the material facts. Is the property a flat or apartment in cooperative society? Does the share certificate relate to the membership in the said society.

How could there be any liability cast upon the so-called legal heirs for a transaction that has been completed more than 30 years ago?

I am afaid the so called lawyers are insisiting upon a procedure which is impossible to be performed that too, in respect of a non-issue.

The apartment share certificate is not a title document.

This certificate will not be considered as a document if the seller is trying to sell his apartment.

The registered sale deed on his name only shall be an authentic document to enable him to sell the property and if there's a defect in the title document then the seller's title in the property will be considered as defective.

Now you ascertain which document need to be rectified.