Property case

Dear Lawyers

My relative in U.S.A. is owner of a property in India.That property in India is under dispute and the matter is in the court.The owner is 85 years old and cannot move.He had appointed his son as his general power of attorney . Can his son who is the GPA appoint special power of attorney to engage a lawyer in India for the disputed property case??

If yes,is  there any authority or other judicial evidence available for this??

Thanks