I have two custom post types - events and items. Items are songs/aria/opera and other musical pieces (please excuse me if I'm wrong with the terminology in English). I created a relationship between events and items and it works great, but since there is a demand to sort items, included in an event, how can I set the order of the items in the event? You will agree that the intro item should be first, no matter what is its post date 🙂 So is it possible to set the order of the related posts in the admin panel when creating an event?
You are referring to the edit screen of the parent post type where you add/connect child posts? Like in my screenshot?
You can change the sort order for that section according to the child post title, or custom fields belonging to the child post, which are set to display as columns.
So in my screenshot, my task posts which are children of projects have a priority field. So I can order that section by the titles of the tasks (ASC or DESC) or by the task priority (ASC or DESC).
So you could add a custom field to your child posts to use for ordering.
But when you change from the default (the title) it only affects the current post being edited, it doesn't persist across to other parent posts when you edit those.