Añadir página y subpágina dentro de wordpress

add_menu_page( 'Imprimir Ticket ', 'Imprimir Ticket', 'manage_options', 'menu-importador','menu_importador' );

add_submenu_page( 'menu-importador', 'Delivery', 'Delivery', 'manage_options', 'delivery', 'delivery');
/*add_submenu_page( 'menu-importador', 'Sincronizar Stock', 'Sincronizar Stock', 'manage_options', 'sincronizar_stock', 'sincronizar_stock');
add_submenu_page( 'menu-importador', 'Sincronizar Individual', 'Sincronizar individual', 'manage_options', 'importar_individual', 'importar_individual');
/*add_menu_page('Theme page title', 'Theme menu label', 'manage_options', 'theme-options', 'wps_theme_func');
add_submenu_page( 'theme-options', 'Settings page title', 'Settings menu label', 'manage_options', 'theme-op-settings', 'wps_theme_func_settings');
add_submenu_page( 'theme-options', 'FAQ page title', 'FAQ menu label', 'manage_options', 'theme-op-faq', 'wps_theme_func_faq');