This is not possible in the core ACF plugin. I have created and example of how this can be done using standard ACF relationship fields, it requires some modification to get it to work with your specific fields and shows the code needed for making the automated updating happen https://github.com/Hube2/acf-filters-and-functions/blob/master/acf-reciprocal-relationship.php
I have also created an add one that automatically does this for all top level relationship fields https://github.com/Hube2/acf-post2post
