CampusDirector offers two options for managing schedule conflicts for registrants/PNMs. There is the Cancel Event Feature and the Excused Feature.
Cancelled Events
If you cancel events for a PNM, it will NOT allow the PNM to be scheduled during that timeframe. This means they may miss out on being able to rank or receive an invite from a chapter they did not attend.
Excused Events
If a registrant/PNM is excused from an event, this will still schedule the chapter for them, but an "excused" message will appear. This will notify a chapter that the individual will be absent, but they will be able to invite them back to the next round, and the individual will be able to rank that chapter.
To use either of these features, check out the articles on cancelling or excusing events.