I’m not sure if it will upload as a fully intact project, but I can try.
For now, I’ll just show what such a Bidule would look like:
It’s simple really…
First, use a “MIDI Splitter” Bidule to separate out each MIDI Channel.
Next, use “MIDI Key Switch” Bidules. This is a very simple Bidule that will transform the MIDI Channel given a specified “Note On” Event.
In the screen shot below you can see where I’m able to “Channel Bounce” between different sounds with key switches in a couple of ARIA Instances that I have set up for Violin 1 and Violin 2.
This is just one way…it could also be done via Program Changes or CC Events using a different sequence of Bidules. There are even more options…such as ‘velocity layers’ (if falls in a velocity range, send to channel 1, if not send to channel 2, etc.), or even splitting a virtual keyboard into ‘zones’ (send one half of the keyboard to one plugin/channel, and the other half to another, etc…even if you need to do real time interval transposition to make it happen as intended). Bidule also has the ability to snoop the MIDI buffer, create more buffers, and even analyze the input and make decisions on what to do next (possibly figure out the tempo as an example, and use that information to decide between martele, sautille, staccato, or spiccato bowing on the fly). This is just the MIDI side of things…we get to manipulate the audio sample data in real time as well 
I’ve got leave my studio for most of the afternoon so I’m a little crunched for time, but I’ll try to offer up an example score/project later.