Licensing a stock image for book with multiple authors

[san5]

I am getting a book published with multiple authors and want to use a stock image on the cover.  We have hired a cover designer who will modify and incorporate the stock image to create the book cover.  

What is the best way to license the image in this case, under the name of the cover designer or under the name of one of the authors? 

The concern is that the multiple authors of the book might all be considered "users" of the stock image.

We are trying to avoid having to create a transfer agreement or buying the license individually for the cover designer and each author.

[Marianne-Deiters]

The cover designer has to license it, not the authors