If using docker, you should just be able to copy the appdata directory. When you start mealie again, point it at this directory (just as you had done before) and everything should work!

I'm surprised that no one has suggested it yet. But, FileBrowser is exactly what you're looking for! Set it up on your PC with docker and point it at any directory you want, put it behind a reverse proxy, make your daughter an account and you're done. It should work perfectly for you as it's designed to handle situations exactly like yours. Willing to help further if you need, dm me.