Author taxonomy and the Workflow module?

I'm trying to have assign multiple authors to a node. I'm able to select multiple authors when editing a node Author Taxonomy (see image1).
The module is working in that I can see that both authors have been assigned to the node (see image2).
However, both authors can't edit the node. I'm thinking this may have something to do with the Workflow Module. I have this module set so that only the author of a node can edit the node (see image3, note this is from the Workflow module).

The outcome is that the author listed in the Drupal author field for the node (see image6) is taking precedence, and only this author has edit permissions. Image4 shows that "Jill" can edit the node, while image5 shows that the other author can't edit the node.

So....would you know if it's possible to get this working with the Workflow module? Perhaps I need to write some kind of query that joins the uid from node and from author_taxonomy_term_list?