Sorry it took so long to get back to this. I would use a bidirectional relationship field. This is not available ACF, but there are two plugins that will do this. Mine is simple https://wordpress.org/plugins/post-2-post-for-acf/. There are others with a lot more features. Or you can code it yourself, there is a guide here https://www.advancedcustomfields.com/resources/bidirectional-relationships/ as well as several others.
