It is now possible to create a subgroup directly from the draft of an event.

You can select one of these lists - all, show up, do not answer, do not show up and then click on the three dots on the right and select "Create subgroup".

Then the window opens where subgroups are created with pre-filled members who were on the list, e.g. if the coach selects the "Attendance" list, everyone who is registered for the event will join the group.