Add Append and Replace options to applying metadata adjustments to images.

What problem do you see this solving?

Currently when you use the copy/apply feature it is impossible to remove existing metadata for metadata fields that can store multiple values. Such as Supplemental Categories, ITPC Scene, ITPC Subject Code, etc. When you copy/apply metadata into these fields it always works as an "Append" adding any new values.

When was the last time you were affected by this lack of functionality, or specific tool?

Today. I've also ran into this a few times in the past. I use both the Category and Supplement Categories fields often and if I mistakenly put the wrong thing into the Supplement Categories fields and apply it to all my images then I'm really in for a long day of pain because the only way to fix that is to individually edit every single image to remove the mistake. This can easily be 500+ images for me.