A project I inherited had a dozen custom post types. Trouble is, they all come off the admin menu sidebar separately. It's not very tidy. Is there a plugin where I can make these subitems of a parent menu, or is there a way, programmatically, I can edit my theme's functions.php to make it make these as submenus?
On the function to register a new custom post type can you set this CPT as Submenu to a exist menu item. Use the param
register_post_type( 'issue', apply_filters( 'wpit_register_issue_post_type', array( 'labels' => $issue_labels, 'rewrite' => $issue_rewrite, 'supports' => $issue_supports, 'taxonomies' => $issue_taxonomies, 'menu_position' => 5, 'public' => TRUE, 'show_ui' => TRUE, 'show_in_menu' => 'edit.php', 'can_export' => TRUE, 'capability_type' => 'post', 'query_var' => TRUE ) ) );
You find the string for the items on mouse over, like
upload.phpon the item Media.