It should be an easier way to add one or several photos to many collections in one operation:
Steps:
Find your photo(s) that you want to add to several collections
Right click to open the rightclick menu
A new entry in menu "Add to collections" will appear in the list
When selecting this entry, the collectionthree will appear
User can expand/scrtoll the three, and tick of several collections that he want the photo(s) to appear in
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