[Adoby]

Yes, this is possible. You do this by customizing the filenames while saving, and then import the books, reading the metadata from the filenames.

1. Make sure you have a good backup of all your books.
2. Save your books using a save template that include the series and the series index as part of the title. Also make sure that you have ISBN and author as part of the filename.
3. Import the books you just saved, and read metadata from filename only. This way the title in the filename will become the metadata title. Read title, ISBN and author from the filename.
4. Fetch other metadata for the books, using the ISBN-numbers, but make sure not to change the titles.
5. Delete the books that don't have the series information in the title.

Done!

I suspect that there is a high risk of making mistakes. Try with one or two books first to make sure you know how to do everything right.