I have a file (attached) that has two data points per series. I select one of the two data points, place a regular line between these two points, and then remove the original data markers (set data marker to 'none').
I would need to apply this only to the selected markers, not the entire chart.
Also, I would need to be able to change the color and the thickness of the line to 2.

There are two graphs attached, one with the 'before' results, and the other with the after results. Any help would be greatly appreciated.