Alternative auto scaling options to "http_service.concurrency"

I am trying to set up a system to have N number of worker processes per queue, for M number of queues. Ex) N = 3, M = 5 results in 15 worker processes. If I allocate 3 workers per fly instance, I would want fly machines to have scaled to 5.

Are there alternative auto scaling options to http concurrency?
Or, can I programmatically manage machine scaling?

When I went through the machines API, it seems to have “start” “stop” api, but if I don’t have an alternative scaling option enabled, I’m concerned that I will be fighting into the auto scaling logic from fly.

Would appreciate any guidance or doc materials I can read further!
Thanks in advance.

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