你想做的事是可以做到的。它不太可能真的干净整洁。

您可以通过使用自定义Walker Class 对于wp_nav_menu() 插入时。

class My_Walker_Class extends Walker_Nav_Menu {

    function start_el( &$output, $item, $depth = 0, $args = array(), $id = 0 ) {
        $output .= sprintf( "\\n<li><a href=\'%s\'%s>%s</a></li>\\n",
            $item->url,
            ( $item->object_id === get_the_ID() ) ? \' class="current"\' : \'\',
            $item->title
        );

        /**
         * Here you will need to add a conditional to see if the parent menu item was found
         * and if so go into a subroutine that grabs your CPT list. Add it all to $output.
         */

        if ( $item->object_id == 111 ) // Match by ID
        {
            // Call external function that generates CPT list
            $output .= my_get_cpt_list();
        }
    }

}

$args = array(
    \'theme_location\'  => \'my_theme_location\',
    \'menu\'            => \'my_menu\',
    \'container\'       => \'div\',
    \'container_class\' => \'\',
    \'container_id\'    => \'\',
    \'menu_class\'      => \'menu\',
    \'menu_id\'         => \'\',
    \'echo\'            => true,
    \'fallback_cb\'     => \'wp_page_menu\',
    \'before\'          => \'\',
    \'after\'           => \'\',
    \'link_before\'     => \'\',
    \'link_after\'      => \'\',
    \'items_wrap\'      => \'<ul id="%1$s" class="%2$s">%3$s</ul>\',
    \'depth\'           => 0,
    \'walker\'          => new My_Walker_Class()
);

wp_nav_menu( $args );