Hi Stephen,
There is no such option however you can easily emulate it - to do this you need to do the following:
1. Calculate the maximum number of stacked bar for all columns.
2. Create that many series.
3. Feed data to each column and fill the remaining series in that column with empty values (double.NaN).
Hope this helps - let us know if you meet any problems or have any questions.
Best Regards,
Nevron Support Team