Add chapters to a book item
I have added a book written by many different authors. Each of the authors has written a separate chapter of the book, so it makes sense to cite each chapter separately. The only way I found out to do that is to duplicate the book item, change the item type from Book to Book Section, and put the chapter name and author into it. But if I do it that way, I would have to manually edit each book section item if I want to change the book information. Is there a more comfortable way? I think it would be great if the Book Section item type could be something like a sub-item to the Book type.
Beyond that, batch editing is planned, but in the meantime, while it doesn't exactly qualify as "comfortable", you can make basic field changes using the Run JavaScript window:
https://www.zotero.org/support/dev/client_coding/javascript_api#batch_editing
https://github.com/willsALMANJ/Zutilo/blob/master/docs/COMMANDS.md#item-menu-functions.
You could also check if the individual chapters are provided on the web, e.g., on the publisher website or by some search engine like google scholar. That's often the case. Zotero's browser connector should then allow to import the chapters. You could then add the chapters as related items of the parent book.
Another relatively easy "batch editing" workflow could be to create one chapter in Zotero and export it as a RIS file. You could then easily create more chapters in a text editor and import the RIS file back to Zotero.