Advice

 a PoA remains valid only till the life of the principal. so your friend power of attorney is not valid.

Thank you for your reply. However in his case what is the best way to move forward to complete the sale deed.

You have to transfer the property as per the will and then the two brothers cans make sale of property. But while registering the sale deed of the property both of the sellers should remain present. So the first part is to transfer of property.

The power of attorney deed executed by mother in favor of her elder son stands automatically revoked/cancelled upon her death.

Therefore the legal heirs of the mother have to execute a registered sale deed in favor of the prospective purchaser jointly.

If this is not possible then the person who is residing in abroad can execute a power of attorney deed and get it notarised by a notary public of the country of his residence or attested by an official of the Indian embassy/consulate.authorising his sibling/legal heir to execute the deed for sale on his bahalf too.

This power of attorney deed sent in a sealed cover to the sibling in India shall be opened by the registrar concerned after which he will adjudicate the same, by which the power agent can sell the property on behalf of the principal. 

If you want to enforce the Will then the beneficairies of the Will have to apply for mutation of revenue records to their name by moving an application before the revenue department. 

For this both have to sign the application or one can move on the basis of power of attorney deed executed by the other in other's favor.  

After mutating the revenue records, the other person can execute the sale deed on behalf of his sibling too by the virtue of POA deed. 

Perfect thank you for addressing each of my points 

no other way.