Affiliation discount management problem with stripe?

Hello everyone !

I'm writing here because I have a problem with managing affiliation discount on my SaaS (tikki.io, only in french at the moment).

We use stripe to manage our subscription payments, and we want to set up a simple affiliate system : users can send a link by email, if the invited person subscribes we offer a free month on the app.

The problem is : Stripe doesn't seem to know how to manage a discount higher than the monthly subscription price. Let me explain: let's say for example that the user invites 10 people that subscribe, he will receive a 100€ discount on his monthly subscription. My problem is that it is not possible to spread this discount every month (10€ per month).

I would like to know if some of you also use stripe to manage subscription discounts related to affiliation? How do you do it?

Thank you very much, I hope you can help me, or at least give me some clues! 😄