[meghane_e]

That's essentially what I do for my Staging library - I use the "Copy to Library" for that.
I just was listing the different libraries out in order to justify my request for information on if there's a way to run multiple instances. Sorry I didn't really lay that out very well...

So if I want to run a backup on my Main library, it subsumes the calibre.exe (on my machine). But meanwhile, what if I want to switch to the Staging library and work on some of the files there?

And as I say that now, it seems like using the CLI for some of that would make more sense, huh? Run the backup from the CLI. Launch the epub editor of files from the CLI.

I guess, I've gotten really sucked into using the UI. ::face palm::