Identify all the students classified as special needs, or who may require longer interviews than the normal single time slot.

Based on parent availability and other considerations such as event congestion, meal break times, likely finish time of the teachers involved, select a suitable time for this student manually, and allocate the interview. Provided there are not large numbers of special needs students, this should not result in any significant loss of solution quality to manually assign a small number of slots. Given the importance of these slots, it is often preferable to assign them manually anyway.

Determine how many additional slots are required, then block out slots out in the teacher’s timetable immediately subsequent to the assigned interview, to mark them as unavailable. This has the effect of booking additional slots so the interview may run to two or three slots as the need arises.

Once these and any other fixed interviews have been assigned (e.g. Specific / restrictive parental time availability, teachers who also have children at the school etc) you can process the remaining schedule via either batch or immediate mode.