How do I make multiple coupon codes available for a single registration?

You can add multiple coupon codes to each or all products/items in the Payment field in the form.

User guide: How to Add Coupon Code to Payment Forms

E. APPLY DISCOUNT TO: Decide where you want to apply the discount.

🔘 PRODUCT - Apply the discount to all or selected products only.

🔘 SHIPPING - Apply the discount to the shipping rate instead of the total.

🔘 TOTAL - Apply the discount to the total amount for payment.

I hope this help. Let us know if you need further assistance.