[Plugin: Co-Authors Plus] Dynamically assign co-authors

Hi,

I’m trying to establish a parent child relationship between users. I have been able to store these relationships using user meta. What I want to be able to do is, automatically assign the parent or the child user as a co-author, whenever one of them creates a new post/post type. What would be the right way to call the function add_coauthors?

Thanks in advance.

http://wordpress.org/extend/plugins/co-authors-plus/