Can I add a book to my TBR pile that does not have an ISBN  ?

Because the TBR pile is for my use and info only, when I have a book with no ISBN, I just type the name of the book in the SEARCH area, and then when the book comes up I just go down until I find one with a 'fake' ISBN and put that one in as my TBR book.  That way I know it's not really a book with a true ISBN. Pat

I just add an ISBN one (if there is one) and use the Note feature to remind me that I need to post it without an ISBN.

I do what Mary does, add an existing listing and put a sticky note on it that mine is a non-ISBN copy. If you wanted to list one there with its own PBS assigned so you can just post from there when you are done, you can do it in a round about way:

1. Put your bookshelf on Vacation Hold just to be sure no-one orders the book while you do this.
2. Post the book using the non-ISBN function.
3. Go to your bookshelf and find the book. Click the +TBR on the listing. You can find it in the yellow popup when you hover over the cover image or on the book details page in Other Options.
4. Once its on your TBR, remove the book from your bookshelf.
5. Remove the Vacation Hold.