You can reserve a demo per group per timeslot. Put your group number behind the timeslot. Example:
08:30-8:50 : Group 1
08:50-9:10 : Group 2
Changes are logged by account. (social security)
9:55-10:15 : -
10:20-10:40 : -
10:45-11:05 : Resit Xenomai : Group 1 (Dimitar & Floris]
Break
11:20-11:40 : Group 20 (Abdulkarim & Simon)
Lunch
13:30-13:50 : Resit : Group 4 (Adriana & Luuk]