Affiliate Commission Calculation Hook/ Process/ Interface?

I am creating an add-on that allows some heavy modification of the affiliate system.

I have a pretty solid understanding of the database structure and have perused through nearly all of the documentation available on WHMCS.com and also searched affiliate related posts in the forums.

Where is the affiliate payment (credit) processed (hook, etc)? Is account credit applied to bill before payment is requested/attempted?

Is it able to be stopped and is it able to be run via CRON?

I would like to tie in to the existing affiliate system and provide an affiliate add-on that greatly increases the flexibility of the WHMCS affiliate system, but the documentation is rather vague...

There are ways around it... e.g. creation of an additional module, table, etc... but this should not be necessary to enhance the affiliate system if there is a hook available that can be used to process additional affiliate processes.

As per much of the posts... I am in agreement that the affiliate system is powerful... but unfortunately, it is also invisible to developers for modification/upgrade/alteration!

Thanks for your assistance!