Shopify plus - Remove discount code box for second orders

I’m looking to adjust my Shopify Plus checkout so returning customers no longer see the discount-code input on their second purchase. The flow is straightforward: the box appears as normal on a first order, but the moment our system recognises a customer has already completed one purchase, it disappears—no replacement message, page redirect, or alternative offer.

Key logic
• The decision must be driven by order history in the customer’s account, not cookies or session tricks, ensuring reliability across devices and browsers.
• Only the discount field is affected; every other element of the checkout, including payment gateways, shipping options and order summary, must remain untouched.

Deliverables
– A clean, documented code change or checkout extension that hides the discount box for customers on their second order and beyond.
– A short walkthrough explaining where the code lives and how to reverse or edit the behaviour in the future.

Please build and test on a non-production theme or a development store before hand-off so I can review the change with no downtime.