I already registered for the conference but at the time the registration for the training sessions was not open yet. I went there today to see if it was open but it's still not. The notes say early 2023 but here we are...
You should be able to Waitlist your training while also adding sessions to the calendar. You cannot "double book" Trainings or UX Labs, but you can "Favorite" sessions and they will be visible on your calendar so that if a spot does not open in the training, you can still see your other interests.