通过添加post_type 到add_submenu_page 菜单slug它将激活CPT页面菜单。然后,您必须使用以下命令将父页面作为该CPT添加到该commnet页面submenu_file 滤器
# Move comment to CPT
function wpse354847_relocate_comments_in_admin_menu()
{
    // Remove existing parent menu.
    remove_menu_page( \'edit-comments.php\' );
    // Move Comments under Complaints (\'complaint\').
    add_submenu_page(
        \'edit.php?post_type=complaint\', //$parent_slug
        __( \'Replies\', \'wpse354847\' ), //$page_title
        __( \'Replies\', \'wpse354847\' ), //$menu_title
        \'edit_posts\', //$capability
        \'edit-comments.php?post_type=complaint\' //$menu_slug
    );
}
add_action( \'admin_menu\', \'wpse354847_relocate_comments_in_admin_menu\' );
# add active page for parent page
add_filter(\'submenu_file\', \'menuBold\');
function menuBold($submenu_file)
{
    global $pagenow;
    if (( $pagenow == \'edit-comments.php\' ) && ($_GET[\'post_type\'] == \'complaint\')) {   // The address of the link to be highlighted
        return \'edit-comments.php?post_type=complaint\';
    }
    // Don\'t change anything
    return $submenu_file;
}