I have modified quite a few Beat Buddy Beats using the FREE Midi Editor called Aria Maestosa. I found out about it from one of the other Forumites.
Although Aria Maestosa is not “feature rich” and the user interface is NOT pretty, it does a good job at simply importing a .mid file from an already existing Beat Buddy Beat, allowing you to modify it (add or subtract beats, change the velocity/loudness of a note, etc.) then export it as a modified .mid file to load directly into a Beat Buddy Manager Song.
@Arizona Mike, I am in AZ also (north Phoenix). Maybe I can help out locally?