If you are using an opt-in page and your only product (intended for this audience) is the SAS system, I wouldn’t bother with any emailing campaigns.
I would either send them ONE well constructed email inviting them to register to the webinar, containing your hoplink, or just sign them up manually to John’s Webinar and let John do the marketing in either case.
If I’d be getting two different email campaigns from two different people/businesses for the same product, I’d unsubscribe faster than the second email arrives