Topic: 2 microphones
I thought I figured this out and one point. But I am only back looking at it now in FL Studio and there are only 2 mics sounding even though I've activated the rest, and I don't see much in the manual about how to use the microphones. The vsts are called 5-out and Reaper does a routing job, in which case they are available.
Normally though, in FL Studio, one goes into the tab in the router where one can create the additional channels.
When I do this in Pianoteq 7 there is only one output (and when I leave its destination blank it works correctly.).
But when I create auto-create outputs, which I do for other plugins to generate the additional sends to the +1+2+3 etc (from the mixer channel in which the vst instrument is aimed, e.g. if the FL Studio channel rack has Pianoteq 7 sending to Mixer Ch 5, then the addition routings would be auto-created (they would be available to manually send as well - which is not the case in Pianoteq.