Assign new user to post when registration form submitted

I have the user registration plugin installed ( V1.4 )

The form I have has both user and post data. An anonymous user "signs up" and creates a post. Currently, the user is created and the post is created. However, the new user is not assigned to newly created post.

I have not been able to figure out what hook to use in order to accomplish this.
This is sort of what I want to do:
http://www.gravityhelp.com/forums/topic/can-a-user-create-an-account-and-submit-post-with-the-same-form

What I have so far:

// set post type and publish status
add_filter("gform_post_data", "ihearditbefore_gform_post_data", 10 , 2 );

function ihearditbefore_gform_post_data( $post_data, $form ){

   $post_data['post_type'] = 'person';
   $post_data['post_status'] = 'publish';
   return $post_data;
}

I notice $form has a post_user [postAuthor] => 13 but it's always the same. I would need to change that somehow — via what hook?

Thank you for your help. Fixed.