As my previous post indicates, the boat's PO did not cancel their Marine SSB ships license, and I now have my own (boat has two call signs). Do I need to do anything?
Don't worry about it. It is the previous owner's responsibility to update the information on his license, not yours. Just make sure the MMSI on the radios is your number and you are good to go.
The FCC holds the license holder responsible for the proper use of the ship license, so I made sure I canceled mine on the old boat. Last thing I wantred was someone hitting a DSC button and having someone knock on my door. Even if it's not my fault, I would have violated the rules regarding keeping information up to date.