My nephew has sole Power of Attorney for his father. Can my nephew add someone else to that POA?

Whether or not he can easily make his brother a POA if the goal is simply to enable him to take care of things he should be able to simply grant approval for his brother to do most things. For instance he should be able to add his brother on HIPPA forms with doctors and hospitals enable it him to get all info and make decisions about care, list him anywhere necessary as authorized on the account, that sort of thing so the brother can pick up the day to day responsibilities of taking care of Dad and his affairs.

A POA written by an attorney may have a provision for the POA to appoint another POA. If it doesn't specifically say that then the POA can not appoint another POA.

Since this sounds temporary is it really needed? Can't one sibling just help out without being appointed POA? I didn't have to show my POA paperwork most of the time. Besides, there are lots of things that we do that don't have anything to do with being the POA.

I agree that he needs to re-read his original to see if there's any provision for adding his brother. "Easily done"? If there's no provision in the original then he probably will need to create a new PoA or some sort of addendum, but he must check the laws in his state. He can have an online consult at legalzoom.com. Much more convenient and affordable than seeing a lawyer in person and you can have consults with actual attorneys who know the laws in his state.

I don't believe that would be possible, but the lawyer who set up the original document could tell you. And as POA the other brother would be able to assign his brother to help with GREAT CARE, as he is responsible for responsible management. Check with the lawyer.

He needs to check the specific language in the document.  I had authority to do this but I don't recall right now what other options were available, or how I would have to perfect that opportunity.

Unless the document has a successor POA, I do not think there is anything he can do to add another POA, only his father can do that. If Dad is mentally competent he can do that.

However as POA, he should be able to assign tasks to others. Not related to banking or finances, but that can easily be done from home bad knee or not.