This is straight from Pub 570:

The Commonwealth
of Puerto Rico
The Commonwealth of Puerto Rico has its own
separate and independent tax system. Although
it is modeled after the U.S. system, there are
differences in law and tax rates.

So, do you have an answer to my question? I know they have to file a federal 1040 for US as they have taxable pension income. They are just living in Puerto Rico - not making any income from Puerto Rico. So not required to file a Puerto Rico return. So are there any tax breaks or am I just looking for something that is not there?