Goodreads Librarians Group discussion

What is the policy on new and revised editions when it comes to combining editions? Is it in order to combine two editions, even if the newest is revised and expanded?

Generally, yes.

Done. :-)
https://www.goodreads.com/book/show/6...

Does that still apply when the revised edition is twice the size of the first editon, essentially making it a new book? I have seen this more thatn once on media tie in books where a few years later there are twice as many episodes to discuss.