As soon as the vst synchronization is fixed this should be achievable like:
https://www.image-line.com/support/FLHelp/html/flstudio_vst_plugin.htm

http://www.energy-xt.com/index.php?id=0115

http://www.musicdevelopments.com/wiki/doku.php?id=rcwiki:vstplugin
"the RapidComposer VST plug-in is a small, reliable plug-in which does not include the whole RapidComposer application as in previous versions, but it communicates with the standalone application through shared memory, also known as 'bridge'. This results greater stability and flexibility.

When the RapidComposer plug-in is loaded by the host (DAW), the plug-in locates the RapidComposer application, starts it, and connects to the application. If RapidComposer was already running, it will switch to “VST Mode” which means the user interface and some internals will be changed."

The vst controller loads into the host and the play/stop events and tempo are synchronized to the main standalone application that runs outside of the host not as an actual vst.
So, you load the biab vst controller into your daw.
The biab vst controller receives the play/stop events and tempo from the host daw, thus playing in sync to your daw.

But unless multriffs are added it maybe better having real band as a vst as it has multiriffs.
This way you may have your tracks recorded in your daw but need some extra tracks added to the session.
So generate them up, hit play on your daw, real band will play in sync with the daw, whatever sections don't fit you simply multiriff them to fit, now just drag the tracks into your daw.
This way you can fine tune the tracks to fit your session and not have to accept whatever whole track that biab generates.



Biab Track Injector for Reaper
Free Biab Chord Picker Tool