If I understand your question, I initially had the same questions as you. As some here on the forums have pointed out, you might want to try opening these files in RealBand instead of BIAB. There you can see all the channels, what instrument is assigned to it and change as many as you see fit.

Win11, Intel i7 7700K 4.2Ghz, 32Gb RAM, 2x1Tb HD, 500Gb NVMe, BIAB/RB 2025, MOTU 828MK3 audio, MOTU Midi Express, Yamaha Montage 7, DX7II, TX802, Motif XS Rack, Roland Fantom XR Rack, Oberheim Matrix 1000, VoiceLive3 Extreme, Kontakt 6, SampleTank 4.3