Goodreads Librarians Group discussion

I'm seeing conflicting answers about whether revised editions of books should be combined together. I think the answer is probably yes based on what I've seen, but I'd appreciate if there are any guidelines for when this shouldn't happen - if the changes are too substantial for example?

I have in mind these books:
Editions 1-3: https://www.goodreads.com/book/show/4...
Edition 4: https://www.goodreads.com/book/show/1...

It's possible these ones have only not been combined because they changed the title.

Yes, they should be combined. Might wish to indicate which are the 4th edition (using the edition fields) first though.