Hello, I need to modify the download process (regarding virtual products).

The mod needed is that the filename of the file to be downloaded must be custom for each order.

Example: product A, filename: test.txt

I want the customer to download this file: order_id_test.txt

This is easy to achieve, simply modifying order.php, but since I have to create, on the fly, the file too (not a problem) and don't want to modify the core file if not needed I was wondering if I could use

$zco_notifier->notify('NOTIFY_ORDER_PROCESSING_ATTRIBUTES_BEGIN');

to call a class where I put

- $filename = what I want
- call external script passing filename, that create the file

May I use that notifier to modify the filename and call the external script?
Is this the correct way to proceed?

Thanks!