Using onAfterOrderUpdate in administrator backend

-- HikaShop version -- : 3.5.1
-- Joomla version -- : 3.8.2
-- PHP version -- : 7.1

Hi, I've been trying to create a function when admin modifies a order from backend, and I've had no luck.. I've tried using variations of below code in order.php (classes and controllers) any help would be appreciate! ( I want to create a function when admin cancels an order, needs to send an API to outside affiliate) Thanks!

function onAfterOrderUpdate (&$order,&$send_email) {
var_dump('ahasdh'); exit;
$config =& hikashop_config();
$confirmed = $config->get('order_confirmed_status');
$orderClass = hikashop_get('class.order');
$orderInDb = $orderClass->loadFullOrder($order->order_id);
if (!isset ($order->order_status))
return true;
if ($order->order_status = $confirmed) {
return true;
}

if ($order->order_status == $confirmed) {

// my simple action to test
}
}

Many Thanks!
Another question if that's ok, I need to store 3rd party affiliate info into the order, what suggested methods would there be? After onOrderConfirm? Is it possible to use cookies when writing functions? Thanks! (Because API info must only be sent if the 3rd party affiliate cookie exists)
Thanks!