Registering Son's Car in Puerto Rico with US Title in Parent's Name

Hi All,

My 26 year old son shipped his car to Puerto Rico. He needs to register it there. The United States title is from a US state in my ( his parent's) name. What documents will he need because of the title not being in his name? I am familiar with the list from the CESCO website and he can meet those requirements except for possibly the clear title (paid off but not in his name). The car is paid off. There is no lien. I am just not sure what will be needed due to the car title not being in his name. We, the parents can sign the back of the title as sellers, but I'm sure there is more to it.  Should he try to get the US Title changed to his name first (difficult as he will need to sign documents in that US state and he is in Puerto Rico) or is there a Power of Attorney we could use in Puerto Rico or even a note from the bank that the car is paid off even though the title indicates no lien or any other required document that would work?  It is very difficult to get an answer from the CESCO offices by calling and also because we don't speak Spanish. Any advice is much appreciated. Thank you!