In addition to the late payment fee request I've seen already suggested, it'd be great to have the option to expire a payment link.

Ideally, I'd love to be able to set options if a payment becomes overdue to 1. Do nothing different; just mark as overdue but amount stays the same and link remains available. 2. Charge late fee, either a flat fee or on an escalating schedule based on time overdue or 3. Expire the link once marked overdue