I design books on a 'for hire' basis i.e. I provide the client with the indd and image link files at the end of the project (once the book has been printed and there are no further revisions to be made).
They have a new editor, who wants to make changes directly in my (unfinished) indd file; obviously, I have refused and said I prefer the usual marked-up PDF which is industry-standard. Hopefully I was clear enough that they will pass that on to the editor.
Has anyone else come up against this sort of thing, and how do you explain to your client – politely and without giving away your workflow – that it's not a good thing for an editor to rummage through a source file willy-nilly, changing what they wish, without any regard for what the designer might have to do to either fix anything they broke, or even find what was changed in the first place?