How do I prevent other red pieces from being selected?

I'm trying to get my mouse to distinguish between a selected checker piece, while preventing any other pieces to be clicked and marked as "selected". In my event, I have the piece Boolean variable named "IsSelected" to be marked as true when it's clicked on. So I know a piece is selected when it's highlighted (take a look at the pic below). How do I also prevent or disable other pieces from being marked or counted as "selected" from the mouse on click condition?

You could set IsSelected to false for the remaining pieces, for example with a ForEach loop, or you could store the UID or IID to a variable instead.

You could set IsSelected to false for the remaining pieces, for example with a ForEach loop

Can you elaborate on this a bit more? Im not understanding how it will get the mouse to not select other pieces.

A few screenshots of both method you mentioned.