I was just writing this (see below), before I saw your post. I strongly support nicobarr's suggestion, thanks a lot for this. I might add that it's still useful that notes are attached to single photos, which allows indeed to work very precisely with the notes tool. I could imagine having 3 different types of notes: 1) notes attached to an item, 2) attached to a file, 3) independent notes, neither linked to an item nor a file, as for example in Zotero.
"I was wondering if there was a way to edit notes that could be attached to the superior item, instead of single image files.
Since there is no way to import files directly from the camera device, I usually create new 'empty' items when in the archives, entering metadata first, and adding the photo files later. In a file that has no photo attached, I cannot edit any note, since notes are linked to individual photos, not to the encompassing item. It would be really useful though to have a notepad when working with the metadata item only.
this is only one possible scenario where a notepad linked to the whole item could be necessary, but I guess there must be other scenarios, so I would be glad to have your feedback on this."