Thanks Jim. Yes the BBPlugin eventually will have all the intelligence within it to do all the functions it needs, it won't be a Biab in the Plugin with 5 million features if users need that then they can use the ReWire VST.
For now the BBPlugin can call on bbw4 to give the text track data as the pic below shows the BBoutput.txt track data, this is saved in SavedTracks when you do multiriffs in the BBPlugin. So rather than waiting all that time for bbw4 to render the tracks to wavs it will just render txt with the WAV Instructions instantly and playback instantly.
Those WAV Instructions in the pic are the same as in the sfz if you drop the sfz into a Notepad you will see.
So in the saved tracks folders you will have just text tracks data and midi data and not a whole lot of wavs that take ages to render unnecessarily.
You seem to be able to get your head around this, I hope others can also.