Question about Recruit a Friend Campaign

[h0tNstilettos]

I believe they have to buy the game first and the apply the code in their Mogstation account before they start paying for a sub.

But even to start the trial you have to register a service account, and the recruitment thing says this: "Enter a friend's e-mail address below, along with a brief message.
Your friend will receive an e-mail containing a recruitment code.
The invitation process is completed once your friend registers a service account using the recruitment code."

That is what's confusing me. I know to continue getting recruitment benefits, your friend has to stay subbed a certain number of days, but the initial entry thing only says registering an account as a requirement, but they already did that in order to start the trial. And as far as I know registering a 2nd account after you already registered was never a thing. Or are you saying that this can be done even if they already registered?