How Biab is now if you have a hold/shot it will mute the UserTrack.
It has been asked for so many years.
An easier way is use Reaper with ReaTrak it will create holds n shots from the Hold n Shots file. So you generate up the normal playing by choosing the instrument and key, then do the same with the holds n shots for that instrument. So highlight the whole song or the section you want, "Choose Instrument" then "ReaTrak Selection".
https://forums.cockos.com/showthread.php?p=2378054#post2378054
once the track is generated you can drag n drop it into Biab.
ReaTrak will open SGU MGU.

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ReaTrak-BB-UserTrack-Set-Red.png (180.62 KB, 43 downloads)
ReaTrak-BB-UserTrack-Set-Endings.png (72.44 KB, 44 downloads)