Well, maybe that was too much in the way of telegraphic shortness ...
Yes, I'm using Cubase 5 - and VE Pro (3 instances, actually) is hosted by Cubase. BUT that doesn't matter much here because I'm getting the MIDI-data to VE via "external" MIDI busses, directly from Sibelius 6. (On my Mac, I can set up new MIDI busses in the Audio/Midi system application. They are provided for by the OS (some "IAC driver", to be more specific) and are offered to all applications. So of course they are really only virtual busses, but to the applications like Sibelius or VE they "look" like coming from the outside world, I guess. ;-) )
- So in Sibelius you can't only just choose any Virtual Instrument as a plug-in, but you can choose to playback any instrument (any staff) e.g. on an "outside / real" instrument like some hardware-sampleplayer (Roland, Yamaha, Kurzweil, you name it) - and in order to do that, you have to send MIDI data to that instrument on some bus (or "port"). Well, it's not like you don't know that.
- Then again, Sibelius doesn't care where the MIDI data goes, outside the computer or to some virtual instrument just "outside of Sibelius". To make a long story short: Name a (virtual) MIDI bus as playback instance, call the appropriate sound set (VSL, of course) and get the MIDI data to any VE instance, be it as a standalone or - as in my case - as a plug-in to a different host.
- With VE PRO, you can choose those (IAC) MIDI busses directly as input. With VE (no-pay-version) I could route the MIDI data via Cubase, Bus 1 connected to VE instance 1, Bus 2 connected to VE instance 2 or whatever.
And - mind you - I'm speaking about MIDI busses, not MIDI channels. Don't get confused by that.
What I'm not sure about is whether my workaround (for e.g. 1st and 2nd violins using the same sound id) also works with two different instances of VE as plug-ins immediately within Sibelius. I'm not sure I tried that. But you may (try), maybe it will work just as well. That way. you wouldn't have to fiddle about with MIDI busses, standalones, extra DAWs or whatever.
(I'm using Cubase mainly because I need the effects - reverb most of all - and some neat recording and editing tools. For my taste the audio export capabilities of Sibelius are really a bit too basic and there is no reverb for plug-in VIs.)
Anyway, my guess is: You simply have to see to it that Sibelius doesn't have to play more than one actual instrument (staff) of the same kind whithin the same plug-in with the same instance of the VSL sound set. Provide for as much plug-ins as you have trumpets or violin sections or whatever.
Well, I hope this is not TOO explicit. ;-) Best, Bernd from Düsseldorf