Add a referral credit to a Client's account automatically

DeanTheTaxGuy

I have a referral setup that gives 25 off to the new client and 25 off to the current, referring client.
I'd like to automate it.
-Client signs up a friend with "first name" "last name" "email address" on my website.
-Client also enters their "first name" "last name" "email address" on my website.
-API from my wordpress form sends that data to Wave API
-Wave automatically creates a new client invoice from the friend's "first name" "last name" "email address" with a $25 discount automatically applied.
-Current client also receives a $25 discount on an open invoice OR a credit on their account for a future invoice.