Sorry: it does not work. I followed your instructions, and I now have:
https://www.inaturalist.org/photos/32540852
&
https://www.inaturalist.org/photos/32540740
for exactly the same photograph uploaded as suggested.
What I want is to use the uploader, and when I am finished have both observations using the same instance of the photograph. For instance: see here:
https://www.inaturalist.org/photos/15372829 (but this was done by a “Duplicate observation”)