I'm a librarian who loves anime, manga, and reading a wide variety of genres.
I figured this out while doing my Rupert of Hentzau post. Even now, when I try a search for "Rupert of Hentzau" in the "Title, Author, ISBN, ASIN" search box, I find nothing that is just Rupert of Hentzau. However, when I tried it as a tag search, I was able to find several posts people had written that were linked to Rupert of Hentzau, rather than an edition combined with The Prisoner of Zenda. I clicked one of those posts, clicked the cover image, added it to my shelves, and wrote up my review.
Unfortunately, this little trick will only work if someone has already written something using the edition you want. It's also only really helpful to those who, like myself, don't really care about the precise edition they're adding.
You would think that searching the book database would bring up every possible edition. I'm not sure why it isn't doing that, but I'll see about sending a message to BookLikes that there's a problem, with Rupert of Hentzau as my example.