See my answer to your post in other thread : https://groups.google.com/d/msg/gatling/bsxN8vuKzKY/xXDGexT0rwQJ
And since scaling out requires a manual intervention, it can’t hardly be done in a single step, at the end of another running scenario.
if you use the scale out feature but you need full gatling download. not sure how to do it with sbt. I have run load test on multiple machines and agregated report using the steps from the following