No: the amount is fixed when the payment is created and forms part of the operation signature, so it cannot be changed afterwards. If the order changes, the old operation is cancelled or refunded and a separate payment is created for the new amount.
If the order changes before payment
- Cancel the unpaid payment and create a new one for the current amount.
- Send the buyer a new link — the old one still leads to the previous amount.
- Give links an expiry so stale ones do not stay usable.
If the order changes after payment
- The amount went down — issue a partial refund for the difference.
- The amount went up — create an additional payment for the balance.
- The order is cancelled entirely — issue a full refund.
How to issue a partial refund is covered separately.
