Right - I think there’s a bit of confusion here.
The referral link doesn’t result in a supplier to client link - they are separate.
The referral link gives you a discount on your power user subscription if another account is set up and purchases a subscription as a result of your unique link.
Whereas a supplier to client link allows you to push invoices from the supplier to the client. From what you’ve said, I believe this is the part you’re having the issue with, as this would be treated differently when “sending an invoice”.
I would expect this link to be removed if the account was completely wiped, in which case, you can set it up again by following this guide:
How to link two QuickFile accounts
I hope this helps, but please do let me know if you need any further assistance.