You can now apply several coupons to a customer account.
When several coupons are applied to a customer, they will be deducted according to the date on which they were applied: the coupon that was applied first will be deducted first.
The remaining value / number of remaining periods for each coupon will be visible in the "Overview" tab of the customer view.
You can also use
GET /api/v1/applied_coupons to retrieve all coupons applied to a customer.