Reference and Compare date fields

I have a node that accepts dates and times that a person is unavailable.
I have another node that schedules the date and time of an event. In this node I have a user reference selection pulled from a views reference of users. I need to pass the date of the event to the view reference for a date comparison, so that the referenced user lists only people without a date conflict with the event date. I've been playing with the relationship utility in the views panel, but can't find the right formula to make this work.
Any ideas?