Add

 function AddOrderProperty($code, $value, $order, $person = 1)
    {
        if (!strlen($code))
        {
            return false;
        }
  
        if (CModule::IncludeModule("sale"))
        {
       
            if ($arProp = CSaleOrderProps::GetList(array(), array("CODE" => $code, "PERSON_TYPE_ID" => $person))->Fetch())
            {

                if ($arOrderProps = CSaleOrderProps::GetByID($arProp["ID"])) {
            $db_vals = CSaleOrderPropsValue::GetList(array(), array('ORDER_ID' => $order, 'ORDER_PROPS_ID' => $arOrderProps['ID']));
            if ($arVals = $db_vals->Fetch()) {
                return CSaleOrderPropsValue::Update($arVals['ID'], array(
                    'NAME' => $arVals['NAME'],
                    'CODE' => $arVals['CODE'],
                    'ORDER_PROPS_ID' => $arVals['ORDER_PROPS_ID'],
                    'ORDER_ID' => $arVals['ORDER_ID'],
                    'VALUE' => $value,
                ));
            } else {
                return CSaleOrderPropsValue::Add(array(
                    'NAME' => $arOrderProps['NAME'],
                    'CODE' => $arOrderProps['CODE'],
                    'ORDER_PROPS_ID' => $arOrderProps['ID'],
                    'ORDER_ID' => $order,
                    'VALUE' => $value,
                ));
            }
        }

            }
        }
    }