Попробуйте так:
add_filter( 'woocommerce_order_formatted_shipping_address' , 'woo_custom_order_formatted_shipping_address',10, 2 );
/**
* woo_custom_order_formatted_shipping_address
*
* @access public
* @since 1.0
* @return void
*/
function woo_custom_order_formatted_shipping_address($address, $args) {
$address = array(
'first_name' => 'ФИО - '.$args->shipping_first_name,
'last_name' => $args->shipping_last_name,
'company' => $args->shipping_company,
'address_1' => $args->shipping_address_1,
'address_2' => $args->shipping_address_2,
'city' => $args->shipping_city,
'state' => $args->shipping_state,
'postcode' => $args->shipping_postcode,
'country' => $args->shipping_country
);
return $address;
}