Stripe promo/coupon codes: redeemable in free trial path

At the moment, coupon/promo codes which are created in Stripe are only able to be added to a customer’s plan if they are signed up but somehow not subscribed to any plan. In the default agency setup, this effectively is never the case; the customer is almost always subscribed to some plan. As a result, the field to enter a coupon code is never presented to the customer.

This is a request to surface the coupon code entry field to people who are already on a free trial. Coupons/promos are a part of the sales enablement process, so this is critical for me, to encourage immediate action from prospects who have sat through a platform demo with me.