You can't have billing emails go to additional people or email addresses?

The Team Billing settings

Billing contacts
Choose who gets email notifications about renewals, invoices, and payments.

If I open this it says

You can have billing emails (like invoices, renewal reminders, and payment confirmations) go to additional people or email addresses.

It only accepts one email address and there is no way to add multiple accounts or see which accounts are billing contacts - its a black hole.

The help says

  1. Add or remove email addresses for your billing contacts, separated by a comma.
  2. Click Save when finished.

This is clearly a bug as the comma separated list is not saved and the first email is the only one you see when opening the option

I reported this as a bug, FYI.