@musocity @Charlie Fogle

I say this to you: You guys are totally Tony Starks!

However, I'm still trying to fathom your wisdom, and may need your further enlightment, or maybe a few screenshots for elaborations.

Here's my interpretation of your explanations, please correct me if I was wrong.

External Audio File (WAV/WMA/MP3)
Sounds easy. Select a utility track, open Audio Edit window, turn on snap, drag the file in, align to the grid, release the mouse, everything will be merged into one mixer track.

The question is, when I save the SGU/MGU file, what's gonna happen? Are these external audio files saved into the SGU, make it a very large file? Or the SGU only saves the path linking to the external files? What if after saving, I rename these exteral audio files, or move them to a different folder, is there gonna be a problem with the SGU?

External MIDI File (.mid)
This is where I got confused. First I open the piano roll window, turn on snap, then what? Should I drag the file in, or copy the file and paste it in? How should I move it to the desired bar grid like I did with the audio?

A Painful Situation
Often I produced these Japanese style anime theme songs, which are quite different from western music. It may sound crazy, but there is a drum fill happening every 4 bars, and each drum fill is significantly different from each other. BiaB generated drum can't do the job, so I need to insert an EZdrummer plugin into BiaB, and drag twenty different 4 bar long drum MIDI files into BiaB, merge them to one mixer track, and play them with EZdrummer. I need to constantly regen short guitar riffs in BiaB until everything matches, that's why I can't export things to a DAW in my case.

So, how should I drag, drop, align, merge all these external .mid files into one utility track in BiaB?

A Canadian music producer, singer songwriter, composer, and professional guitarist.