Using this method will expand the capabilities of the Biab Plugin no end. (see note below)
It is using one Biab Plugin per track.
Each instance of the plugin will open the same song.SGU
It will allow you create and mix before dragging any tracks into the DAW.
All selected tracks in all plugins are being play back (from the local folders) together in sync to each other and to any existing track in the DAW.

On the Drum track we select RealDrums for each "Special Track"
just add the drums you think would fit best, you can have 7 of them.
On the Bass and other tracks do the same.
On the soloist we choose MultiRiff and the RealTrack
the bars where we want the soloist we highlight to select the region, select Generate MultiRiff Selected Region.
We can use Direct Input RealTracks and load a guitar FX VST like Amplitube or Guitar Rig after the Biab Plugin.
Any sections can be regenerated with MultiRiffs and slipped in to that section of track in the DAW.
We have a midi track with the Biab instrument Plugin that has a selection of midi piano tracks, after the Biab instrument Plugin we have EZKeys VSTi.

You can also add any other FX after the other Biab Plugins.
Remember you have Band-in-a-Box DAW VST FX Plugin.dll for audio tracks and Band-in-a-Box DAW VST Plugin.dll instrument for midi tracks.

So in the Biab Plugin preferences we have "Sync Playback checked"
We now bring up the Biab Plugin on each DAW track and after generating "All Special Tracks" we select the first track we would like to play back in sync to preview.
You can loop a section in the DAW while changing tracks in each plugin, by selecting another track in the Biab Plugin and hitting the Biab Plugin Play button (this will be made easier soon, see below).

**Points to note
these things are on the to do list to be fixed as from current 1.14.2.0
Generating RealDrums in the 7 "Special Tracks" will all generate the same drums as the style's drum no matter what drum you choose.
DI Guitars are not selecting.
Select multiple tracks in the Plugin to play/stop with indication on each track,
like green play arrow or red stop square that toggles to indicate state.
"Sync Playback" moved from Preferences to a button.
At the moment the Plugin GUI needs to be opened to play, so you will need to leave the Plugin windows open.

Attached Files (Click to download or enlarge) (Only available when you are logged in)
Reaper-BB-Multi-Plugins01.png (368.83 KB, 68 downloads)
Reaper-BB-Multi-Plugins02.png (345.95 KB, 68 downloads)
Reaper-BB-Multi-Plugins03.png (346.28 KB, 68 downloads)
Reaper-BB-Multi-Plugins04.png (360.45 KB, 68 downloads)
Reaper-BB-Multi-Plugins05.png (384.4 KB, 68 downloads)
Biab Track Injector for Reaper
Free Biab Chord Picker Tool