Parallel testing summary report

Hi,

I'm using parallel tests to improve one of our long running tests and it's working great up till the final step.

We need to generate a custom report containing all of the data. So i've got my 50 test cases split into 5 10 row reports. Now i need to merge them which is easy enough to do but I cant find a way of triggering something to run after the composite build is complete. I'd just like to trigger a powershell script within the build.

I've managed to add another build with a finish trigger and build the report there but then the report is no longer an artifact of my actual test run. I also couldn't find a way to upload a new artifact into the test build via the api.

So really what i'm after is a final build step that just runs once, once the composites are all finished.

Any ideas?