Answered by myself: uploaded all 96 presets as zrm files, permutated as needed, downloaded again. Pretty challenging, but once you get the idea is rather straightforward. An "upload all preset" soft button would have been nice to have, anyway. No need for external editing thanks to the - this time - very useful touch screen interface.
After that you can use the wheel to select banks and four hard buttons to jump from one registration to the next. You have to remember to change bank every four registration - wheel clockwise action or ^/yes button if you have banks selected on your touch screen interface - anyway.