Hi Derk,
I’m sorry I think I misunderstood your question.
I believe you want to add an admin column for the post list on the backend. For something like that, please take a look at this page: http://www.elliotcondon.com/advanced-custom-fields-admin-custom-columns/.
Keep in mind that it’s an old article, but I guess it’s still applicable. You can also check this page to learn more about it: https://www.smashingmagazine.com/2013/12/modifying-admin-post-lists-in-wordpress/.
Thanks!
