RIght now the only way to register a contact to an event without them landing on a page, is to register the contact one by one in the event settings.
Suggesting adding a bulk action option to register to event.
Use case: Let's say contacts went through a funnel before an event was created and we want to show the users a sales countdown timer in an email. The timer is linked to an event, and we have to register the contact to an event before the email timer will sync.
Adding this feature will provide an easy way to do this.