Identifying Overlapping Date Ranges Dynamically

I have a simple table of 12 events, the important columns for this problem are "Start Date" and "Suspense Date." I need to identify exactly what dates overlap between two or more events. I can't use macros because of security reasons.

The ultimate goal of this is to color-code a calendar. Conditionally formatting based on the start and end dates is easy. Formatting the overlap is giving me trouble.

The intent is that the only user input required is adding or removing events from the table.​

I've tried generating lists off all the dates on which any event occurs and finding duplicate values from there, but that slowed down my worksheet too much to be usable.