I have an upcoming webinar set for people to join by registration. In order to leadership not have to register themselves, we added them in as optional presenters (this was the only workaround we found possible) therefore, they find an invite instead to have to register. Now I need to add a colleague who will help me co-hosting the event, according to the guideline I need to add this person as optional presenter first. However, if I update the invitation, it will send a update to all invitees. I already tried forwarding the event to her. It did not work.
Apologies for the delay in responding - when you add another presenter to a webinar, it will send the update to all of the directly invited folks (the other presenters), but not any attendees.
When you forwarded the event, what exactly "did not work"? Was it that she was not a presenter? If so you can adjust that in the meeting options for the webinar (or promote her in the webinar as it is running).