I’ve just dealt with something similar. My mum who I always took cruising is now in a nursing home. Just prior to final payment my Celebrity TA (who was so sad at the news) said she would just be a “no show” at boarding or we could do a name change for free. Ends up I’m taking my sister - all my reservations etc I’d made for my mum were transferred to my sister’s name.
I am so sorry for your loss.
Wendy