最后，我找到了一个有效的解决方案。卡通系列可以像你一样注册，但剧集自定义帖子类型不能是hirchical（我认为WordPress希望父内容与子内容的类型相同，如果使用post_parent 在里面wp_posts 数据库表）。

注册剧集时，重写规则必须设置为所需的slug，即cartoon-series/%series_name%. 然后我们可以筛选要替换的剧集链接%series_name% 具有父级的实际名称cartoon-series 帖子类型和重写规则，用于告诉WordPress何时需要卡通系列帖子类型，何时是剧集。

add_action(\'init\', function(){
    $labels = array(
        "name" => "Cartoon Series",
        "singular_name" => "Cartoon Series",
        "menu_name" => "Cartoon Series",
        "all_items" => "All Cartoon Series",
        "add_new" => "Add New",
        "add_new_item" => "Add New Cartoon Series",
        "edit" => "Edit",
        "edit_item" => "Edit Cartoon Series",
        "new_item" => "New Cartoon Series",
        "view" => "View",
        "view_item" => "View Cartoon Series",
        "search_items" => "Search Cartoon Series",
        "not_found" => "No Cartoon Series Found",
        "not_found_in_trash" => "No Cartoon Series Found in Trash",
        "parent" => "Parent Cartoon Series",
    );

    $args = array(
        "labels" => $labels,
         "description" => "",
        "public" => true,
        "show_ui" => true,
        "has_archive" => true,
        "show_in_menu" => true,
        "exclude_from_search" => false,
        "capability_type" => "post",
        "map_meta_cap" => true,
        "hierarchical" => true,
        "rewrite" => array( "slug" => "cartoon-series", "with_front" => true ),
        "query_var" => true,
        "supports" => array( "title", "revisions", "thumbnail" )
    );

    register_post_type( "cartoon-series", $args );

    $labels = array(
        "name" => "Episodes",
        "singular_name" => "Episode",
    );

    $args = array(
        "labels" => $labels,
        "description" => "",
        "public" => true,
        "show_ui" => true,
        "has_archive" => true,
        "show_in_menu" => true,
        "exclude_from_search" => false,
        "capability_type" => "post",
        "map_meta_cap" => true,
        "hierarchical" => false,
        "rewrite" => array( "slug" => "cartoon-series/%series_name%", "with_front" => true ),
        "query_var" => true,
        "supports" => array( "title", "revisions", "thumbnail" )
    );

    register_post_type( "episodes", $args );

});

add_action(\'add_meta_boxes\', function() {
    add_meta_box(\'episodes-parent\', \'Cartoon Series\', \'episodes_attributes_meta_box\', \'episodes\', \'side\', \'default\');
});

function episodes_attributes_meta_box($post) {
        $pages = wp_dropdown_pages(array(\'post_type\' => \'cartoon-series\', \'selected\' => $post->post_parent, \'name\' => \'parent_id\', \'show_option_none\' => __(\'(no parent)\'), \'sort_column\'=> \'menu_order, post_title\', \'echo\' => 0));
        if ( ! empty($pages) ) {
            echo $pages;
        } // end empty pages check
}

add_action( \'init\', function() {

    add_rewrite_rule( \'^cartoon-series/(.*)/([^/]+)/?$\',\'index.php?episodes=$matches[2]\',\'top\' );

});

add_filter( \'post_type_link\', function( $link, $post ) {
    if ( \'episodes\' == get_post_type( $post ) ) {
        //Lets go to get the parent cartoon-series name
        if( $post->post_parent ) {
            $parent = get_post( $post->post_parent );
            if( !empty($parent->post_name) ) {
                return str_replace( \'%series_name%\', $parent->post_name, $link );
            }
        } else {
            //This seems to not work. It is intented to build pretty permalinks
            //when episodes has not parent, but it seems that it would need
            //additional rewrite rules
            //return str_replace( \'/%series_name%\', \'\', $link );
        }

    }
    return $link;
}, 10, 2 );

NOTE 2: 可能需要添加更多的重写规则，例如用于分页帖子。此外，它可能需要更多的工作才能获得完整的解决方案，例如，在删除cartoon-series 是否也删除所有子集？在“管理编辑”屏幕中添加过滤器，以按后期家长筛选剧集？在管理编辑屏幕中修改剧集标题以显示父剧集名称？