I'm looking in the help file under Index="Chord List".
Perhaps this will help (down at the bottom) it reads:
Add your own chord shortcuts.

And further states, "Note that this file doesn't ship
with Band-in-a-Box (or it would overwrite your file!).
The file \bb\pgshortc.txt for shortcuts is supplied by
PG Music. You can add your own shortcuts in a text file
you make yourself and name \bb\shortcut.txt".

Hoping this helps you out.