**This is NOT about the "Forward To a Friend" function**
I send an email about an event with a registration link.
The recipient forwards that email to one or more people, but does not register for the event.
Recipient still counts in a campaign as "unregistered" and receives follow up notifications as part of the campaign.
The people who received the forward register for the event, but are not contacts.
How would you associate the forwarded email and subsequent campaign actions to the original recipient?