I have always carried a donor card, although it is not necessary in France as it has the 'opt-out' system. I told my daughters and one said that of course she would carry out my wishes, but the other said she would not as she could not bear to think of me being 'cut up'. This the same daughter who has now completely rejected me, so I am glad to be going to live near the other daughter in New Zealand.
Surely, the last thing your relatives can do for you is to honour your wishes.
Bluebell, we need new perspectives on old issues, so please keep posting.