Conrad. My 'proposed' solution notwithstanding, the date approach works as well. All that is really needed is some type of value to reference in your conditional.
I did a search for conditional recalculating at Microsoft and got 'bumpkis' (typically).
There is a bulletin board like site I used years ago that is populated with Excel Geeks way beyond you and I. It's free. You may need to register to ask a question, but the price it right.
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