Hi Leo

Hmmm well as you know the problem stems from only having one vst as the default
Synth in BIAB

Midi normally get put on the melody track this uses channel 4.
You can check what channels BIAB is using for what, by going to Options preferences Channels.

Any midi data on the melody track gets sent on that channel.
If you are using Kontakt as your default synth and with just one instrument it will play the midi from the melody track if you select omni or port A from host ch4.
If the Kontakt is a multi instrument then each instrument in the multi can have its own channel.
Therefore if the midi in BIAB melody track is a multi channel midi then each track/channel in the midi file will play though the appropriate multi instrument assigned to that channel but the whole lot still gets sent to Kontakt over the melody channel 4
Also remember once you insert Kontakt as your default vsti synth that you will not be able to play the midi BIAB style parts unless you have appropriate voices in the corresponding BIAB part channels as above channel preferences in your multi.

Hope this is some help I will have a play tomorrow as it is 3 am in the morning here and time for some nod methinks,
Mike

BIAB2021 UltraPlus,AsusN55S1Tbssd, W10/64,Akai EIEpro
Yamaha CVP405,SquireStrat, CoolsoftVMidSynth
Novatation Impulse61 Ctr kbd, Cwalk blab Kontakt

http://mikesmusic.byethost16.com/