I can't easily recall the post, but I do believe that if A and B are validly exempted (meet all the requirements), that they don't factor into any calculations. C stands on it's own; it transactions are under the amount, a CTR doesn't get filed; if over, it is filed.
If I'm incorrect, I'm sure someone will point that out.
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I hear and I forget. I see and I remember. I do and I understand.--Confucius