It took a time where I needed to relocate my wallpapers directory to a sub-directory and I had stalled it because I knew this would break the Gnome themes i had made. But after looking at how Gnome themes are saved this isn’t a really a big deal.
gnome-appearance-properties creates basic text files with that contain the theme information. In the directories
index.theme files where the information is kept. A text editor can edit the files easy enough if there aren’t many of them, but I think it’s easier to run
sed. Sed is an amazing utility to replace and change text I’m discovering. I noticed a good number of tutorials around the net on sed. Programmers seem very adept at using it.