Box Overlay On Stacked Bar Chart

[RichB]

Hello,

Is there a way I can create a bounding box on my stacked bar chart?  The goal is to illustrate that certain periods are part of a single process.  I don't know if this possible to do within a stacked bar chart, so might it be possible to overlay two graphs charts or images to create this affect?

I would like to produce the bounding boxes around segments of my stacked bar chart as shown below.

Thank you!