The prefix idea has merit. The other alternative, of course, would be to delete all tags & replace them with the ones specified in the form (the form would be pre-populated with the current tags when editing the page, I assume)
What would be perfect, though not necessary, is an alias for each tag. For example, my "Three Word Category" could be represented by the tag _3 , and I'd want to show 'Three Word Category' to the page creator, instead of the actual tag name.
Re: parents at creation
Exactly. So for me, that would work well. For someone else, they may also need to convert a plain text field that the page creator enters, so that it's the parent of the page?
The thought crossed my mind that the field might be something like C:\user\shane\desktop\image.png, but if it's just the filename, that works fine for my own needs, at least.