Partner Program - Single Attribution on Payment Plans

Right now the Partner Program handles products that are set to "Payment Plan" on checkout, as crediting the affiliate per payment that the end user makes.

Example: a $100 product on a payment plan of 4 x $25 on checkout with a commission of $20 will credit the affiliate $20 every time a payment is made (so 4 x $20), even when the order quantity is one.

Can we add a setting that allows us to set only one commission per product, or commission on first payment only?

Thanks!