Block reviewers' calendar with potential time slots

We need to guarantee that the reviewers for a meeting have their calendar blocked for the available slots that are displayed in our Scheduler app. Currently those invites are manual and are creating confussion.
It will be ideal if the scheduler app send a placeholder to the reviewers when a time slot is set.
Other questions to consider:
- Is there a way to update an instance of that placeholder with the actual meeting once a team schedules that time slot?
- Outlook manages expiration days for meetings, how does that work with the scheduling tool?

Start by locating the Scheduler app's time-slot and reviewer-invite flow, then review how Outlook handles placeholder meetings and expiration. The work is complete when available slots create reviewer placeholders, selected slots can become actual meetings, and expiration behavior is defined.

Written by the indexing model from the issue text.