So why not create a custom column - series type, with a name of version, then have a new copy of the file in a new entry, with the 'version' column containing the title of as the series and the version number as the series number.
I'm curious, How do you (OP) store your different versions at the moment.
Say just taking the three types as your example, DRM, NonDRM and Edited, how would you store the files for say author:John Doe, with title:The First One, series:The Book List, series_num:01
First off I would leave the DRM'ed files in their original download/store folders.
Then create a folder for DRM removed files (matching directory structure as DRM folder)
Import these (NonDRM) into calibre, with custom column (series type, called editversion)
Whenever you edit a particular entry, just create a duplicate entry with the same metadata, using the entry's title as 'edit_version' (series-name), and updating the 'edit_version' series number to store your revision number.
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