The schedule automatically caps at four students so it doesn't overschedule a group for you. However, you can manually add as many students as you would like to a group!

To do this, drag the student who needs to be scheduled from the 'Service Times' area to an existing group.

You may see that you cover up another student's name in the group when you do this, but all students in the group will show up correctly on the schedule printout and in the daily data agenda.