I add the post-to-posts code to my functions file, and all works fine.
When I relate 2 post_types together, 'movies, actors', I have the ability to choose an actor when edit/add a movie in the admin UI. Works as expected.
Right now the actors box shows up on the right, and I can only select an individual actor as it's a dropdown choice.
Is it possible to change that box where I have checkboxes instead of a dropdown choice, so that when I am adding actors to the admin UI for movies, I can select multiple actors to relate to the movies post_type?
As it is now, I can only relate one actor to a movie, trying to figure out best way to relate multiple actors to a movie via the admin UI.