Unfortunately, it will require some custom drawing to get a stacked bar on top of one of the other bars in the series. If you use a stacked bar chart type, you can stack bars, but you don't get the same series grouping you get with a regular bar chart. To get the chart in your image, you will need to handle FillSceneGraph event, find the right coordinates for the new bar and add a box primitive to the scene graph at those coordinates.

You can refer to the following help link for information about using FillSceneGraph event:
https://es.infragistics.com/help/aspnet/chart-access-axis-inside-fillscenegraph-event-of-a-non-composite-chart