Yes, that was my proposal to simplify drag/drop adding of multiple ebooks of different formats. (I suggested using the shift key to signal when drag/dropping multiple ebooks that they should all be considered the same book.) I was tearing my hair out to speed up my entry process. It had stretched for months, but that was a particular annoyance - drag dropping multiple formats of a single ebook always created multiple entries. I was adding a single book, opening it to edit, then dragging in the other 2 formats, rinse repeat - it was taking forever.
I still think it's a good idea, but it is nowhere near as helpful as the code I've got now. With the new code I can drag drop 150 files comprising 3 formats of each of 50 books and all end up where I want - in existing records, where possible, and otherwise in new records with the multiple formats all in the same record. The shift signal would require 50 drag drops and I'd still need to deal with the issue that any existing records for the same book would block the new formats from being added.