Combining eBook with no ISBN?

Recently purchased Hunter's Redoubt by Michelle West in both hardcover and Nook eBook editions. Hardcover and paperback have ISBNs, eBook does not appear to. When I try to change the eBook cover, which currently shows as my default, to the correct one, it changes the ISBN to the hardback. What does LT say about combining them? The only other person with the book on LT is using the paperback ISBN for her ecopy.

>1 leennnadine: others will have better answers. usually when i change a cover, it asks me do i want to change isbn too. hit no and u can use whichever cover u want.

books are combined by title/ content - not isbn. all books of that title should be combined, unless one contains additional content.

The possible ISBN change happens when you select a cover from Amazon (but there is a checkbox that you can unselect if you don't want that behavior). If you pick a member-upoaded cover (or provide one yourself) you will not experience that problem at all.