Is it possible to have someone register for multiple sub-events?
Yes. But, their dates and times can't overlap. When they check the box for one, it will grey-out any other sub-events within that event that would conflict.If you want them to be able to select multiple options from a list, you can use custom fields or fees.
Excellent. Thanks Erik! I could have sworn I had done it in the past but it has been a few years and I couldn't figure out why they were greying out.