Dear Mike,

The codes didn't respond unless I enter 1 or 2 manually in cell A1.

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In cell A1 of all 28 sheets, I was thinking of using a Reference formula,
IndexMatch(ing) from the helper worksheet.

In Cell A1 of Sheet 1-28
a) =if(iserror(index(Helper!B1:B100,Sheet1!B1,Helper! A1:A100,))),2,1)
b) Sheet1 B1=is a Worksheet name formula

That way, I can centralise control over the sheets. There will be lots of
hiding & unhiding (kinda dynamic). lol.

Thanks.