[Starson17]

This request is a book editing function, and I'd rather that Calibre focus on its book cataloging function.

However, I'd very much like to see Calibre eventually offer a "Send to Editor" function. Currently, you can select internal viewer or external viewer, and if you like, you can change the external viewer to an external editor.

For text format, my external viewer is also my editor, but I'd like to be able to read EPUBs with the Calibre viewer, and separately "Send to Editor" to send it to Sigil.

For editors that have the capability, it would be nice to be able to send multiple files to the editor. Then the OP could send his 3 pdfs to a pdf editor (Send to Editor would have a pulldown of formats, allowing multiple books to be selected and send the pdf format from each book to the defined editor for pdf format). He'd then use the merge function to collapse the records into one.