Charting multiple data types on a dashborad


I want to have chart on a dashboard that shows a line graph of pressure over time. I'm able to do this pretty easily. What I can't figure out is the following:

I have rows in the data source report that have a date and a checkbox for filter changed checked. I want these to show up on the chart as either dots on the graph or vertical lines at their date. This way the user could easily see the pressure over time and when the filter was changed.

Appreciate any help, thanks.