Turning an excel cell into a check box - but selected cell range only not the whole sheet

I really like the answer to the first part of my title found in this thread Turning an excel cell into a check box

The code they gave to do that task is as follows:

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But can anyone tell me, how would I modify the above code to target only specific cells that are double clicked and not the entire sheet? For example just a range say A:1 through C:20 or multiple ranges on the sheet A:1 through C:20 and A:26 through C:46 or similar.

Also

How about the ability to remove the check mark if the cell is double clicked again?

In this example, there are two ranges A1:B20 and D1:D20
I have added the option to clearcontents if it already contains a checkmark.

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Does that work for you?