Designed a custom publish type, "Occasions", great. Now I wish to obtain a second custom publish type and nest its menu products using the existing Occasions products.

  1. No taxonomies permitted
  2. I understand there's great event plug ins, case theoretical
  3. It's gotta walk inside the "Occasions" menu, not below or above!

Ought to be straightforward... right? ...guise?

Take a look at http://codex.wordpress.org/Function_Reference/register_post_type and also the bit about "show_in_menu".

You need to have the ability to place it to something similar to:

'show_in_menu' => 'edit.php?post_type=events'

And will also appear for the reason that menu. For additional control, you could have fun with the $menu and $submenu global variable. Add both publish_types, perform a print_r on $menu and $submenu to determine where things are, after which move several things around. It'll most likely look something similar to this:

add_action('admin_menu', 'change_zee_menu');
function change_zee_menu() {
    global $menu, $submenu;
    $submenu['edit.php?post_type=events'][13] = array(
            0   => 'All Sub Events',
            1   => 'edit_posts',
            2   => 'edit.php?post_type=sub_events'
    );
    $submenu['edit.php?post_type=events'][14] = array(
            0   => 'Add Sub Event',
            1   => 'edit_posts',
            2   => 'post-new.php?post_type=sub_events'
    );
}