It is possible to fill a slot in th schedule that has taken place in the past. This is useful for assigning ftms retrospectively to keep records correct and to allocate costs. However, when an appointment is deleted in the past the slot becomes grey and there is no way to open it up again. 2 things need to happen here
1) We need to be able to edit the slots in the past
2) If a time slot is deleted it becomes open by default, not closed and greyed out as it is now.