OK, I did quite a bit trial and error and found that if
- the options/output/Mobi/"use author sort order" is checked
- a plugboard that maps {author_sort} --> authors is set up
then the Kindle sorts on Lastname but displays "Firstname Lastname". By now, I'd be very happy with that solution.
However: I also notice that if a book was already in a Collection on the Kindle before one sets the aboue settings and pushes the metadata new, then the collection is not updated, i.e. will still sort incorrectly. I had to manually update the collections by taking each book out and in again (best done inside the collection with the multiple books add facility, every check mark needs to be taken off and put on again).
Isn't this depressing?
Regards, Mixx