Line and Clustered Column Chart

Hi.

I am currently using the Line and Cluster Column chart within one of my reports (see below). Ideally I want the Line element of this chart to show discrete values only and not a continous line.

For each grouping in the chart (can  be seen by the green/black/red bars) on the second Y-axis I want to plot a discrete value so effectivly only one plot per grouping.  This chart joins the discrete points into a line.

I aprreciate that this chart is designed to work this way, does anyone know of any other available visuals which would allow me to do what I want?