Account Upgrades Question


I was wondering if there's anyway to create a field that must be completed by the user when they're upgrading their account? I run a Minecraft server, and I charge $20/month to be on it, and I need their Minecraft name to whitelist them, and I need to send them an email after paying with more details. Is there anyway to set something like that up with XenForo?

tl;dr When someone wants to buy an account upgrade, I want to force them to fill out a field (their Minecraft username) and I recieve that once they upgrade/pay. I also want them to be auto-sent an email with more details right when they pay/get upgraded.