Flagging Dates within range intersecting other date ranges

[_MANNY_]

Hi guys. ideally on Excel 2010 but if a function of later versions id still be curious, is it possible to flag entries where a date range (within a list), overlaps or intersects with another entry in that same list or other lists.
I want to introduce a flag system of DQ checks for data entry folk. The exact model is a little complex to explain, so I have used this simplified example
Basically we have a number of different types of data ranges (each on many worksheets - so a single helper page is NOT an option)
Each list contains a "from" date and a "to" date

It is easy to overlook or typo dates already in the lists, but also we need to identify when they overlap or surround other entries

curious if we can "text flag" the nature of the return (ie "date is contained in list C", or "This overlaps with another entry" kind of thing)

The list format and mechanism can not be amended - were are stuck with what we have

I have played with the sumproduct countif, but this only seams to work to identify duplicate single dates - I need to explore within each range
Sure it will be a CSE but I'm stumped

Example shows expected results

As always thanks guys

[dosydos]

Personally, I think a Macro would make the best solution for this problem. Maybe something with a visible command button to initiate the check.