Use BeforeDoubleClick to sum cells

Hello

I have column L and it will be various of number of rows, is it possible to use doubleclick in cell L20, L21 and so on to sum M17+M16+M14, and sum it in cell L20, L21and so on, or must i use another emty cell to double click in for each row and how will that vba look like

The values in M17, 16 and 14 will change often