I know this is an old topic, but since I myself searched for a solution recently, here is what I found: this can be done by passing the number of charts as a parameter. Nevron Chart for SSRS supports unlimited number of chart areas so all charts can be displayed in a single chart report item. The visibility of the chart areas is specified based on the parameter. The width and height of the report item can also depend on the passed parameter.

You can also use a tablix/matrix report item and configure the chart inside the grid.