You can add elements to a period the same way.
If you want to add a class, select the class you want to add in the "Classes" dialogue window by pressing the Ctrl. key.
In the substitution window, this is shown as "Lesson changed". In the "Class" column, both classes are displayed, the original and the added class. If the added class has already a lesson scheduled for this period, additionally a cancellation is generated for the original lesson.
You can add a teacher to a lesson by using the "New teacher" function. A second tab is created which already holds all information on class, subject, room and student group, you only need to choose the teacher.
Consequently, a special duty is generated for the added teacher. If this teacher has a lesson at the chosen time, an unscheduled substitution or cancellation is generated.