Basically, we've been able to solve the issue using the servicemix lock - servicemix doesn't start when using the lock, so the embedded broker doesn't start either.

One annoyance note though:

we had to use:

karaf.lock=true

karaf.lock.dir=X:/nodeA

karaf.lock.level=20

karaf.lock.delay=10

instead of

servicemix.lock=true

servicemix.lock.dir=X:/nodeA

servicemix.lock.level=20

servicemix.lock.delay=10

because "servicemix" has been replaced by "karaf" on system.properties

this wouldn't be so annoying if we didn't have to guess it by ourselves - we couldn't find anywhere where this was listed. But all is well when it's well.