I too have this same question. Doesn't look like it's possible.
I have found a work around by running a summary table and then using graph builder to make the display come out correct, but it would be way nicer if I could easily have a second category in the pareto chart function.
![9667_stacked_pareto.png 9667_stacked_pareto.png](https://community.jmp.com/t5/image/serverpage/image-id/2117i0D2A9094C819E130/image-size/medium?v=v2&px=400)