This is what I’m stuck on. Since A doesn’t exist, I do not have their userID. So how do I find the file that was originally uploaded under this ID in order to remove it?

I guess I could add another field to a user Thing along the lines of “pre-registered user ID” and, when I create the actual account (user B), I can save the “current user ID” into that field. Then my ‘delete original image’ workflow would reference that ‘pre-registered’ userID. But man, that is not very elegant!