Came upon a quite similar scenario as described HERE: event 1 (initial workshop) is the kickoff-"lesson" for two types of event-series, which will continue in two different date sequences afterwards.
The scenario: event 1 is an initial workshop-lesson of an event-series continuing during the whole year AND it is the first date of an intensive short training course of one month.
With the advanced events extension for the additional event registrations and using price sets, I could easily achieve the desired registration behaviour for both of the event-series.
But: How can I define two or multiple additional event types for the first kickoff-event? Using custom fields is not an option, as the event types are predefined in CiviEvent.
Any hint would be highly appreciated. Most probably, I don't realize at the moment, that there would be an easy solution.