Hi @hexardan
Hmm… It may not be possible to assign a category to a field. ACF does not have such a functionality.
May be you could consider a different implementation: Attach all the field groups to a single post, then use meta_query to query the fields and get_field(…) or the_field(…) to display the fields’ value on your templates.
Have a look at this tutorial for more info on this: http://www.advancedcustomfields.com/resources/query-posts-custom-fields/
Hope this helps 🙂
