How to change a book to be an edition of another book

[anna]

I added two books but later realized one is just a different edition of the other. How do I fix it?

Original book: https://www.goodreads.com/book/show/6...

Other book that's actually just an updated version of the first: https://www.goodreads.com/book/show/6...

[Renske]

I combined them. You need to be a librarian to combine existing books.

[anna]

Renske wrote: "I combined them. You need to be a librarian to combine existing books."

Thanks