We'll create fresh WordPress site with Post to Menu installed. You have 20 minutes to test the plugin after that site we'll be deleted.
Add pages, posts, or any other custom post types to any of your registered WordPress menus directly from the post editor page. Check the checkbox for the menu to add a the post / page / custom post type to, update the post / page / custom post type and it will then be added to the top level of all the checked menus.
You can control which post types display the ‘Add to Menu’ meta box by going to the ‘Settings > Post to Menu’ page.
If the post type has hierarchal structure (such as parent Pages), this will try to place the new menu item underneath a menu item that links to an ancestor post (if menu item exists).