hidden voice

[Yohann Martineau]

hello,

I'm using lilypond to write scores for bagpipe.

I've seen that it was possible to create midi file using lilypond. 
That's really great. I've created my main melody, but now I would like 
to add drones in background.
Drones are not permanent in my track, so I'll probably have to create a 
new voice or a new staff dedicated to drones. That's not a problem. But 
I would like to hide it in the generated pdf/ps. Is it possible?

I've seen that it was necessary to write another score with 
\unfoldRepeats to have repeats in midi, it's ok but is there a way to 
"include" the previously defined score? I fear copy/paste because I may 
forget to do it once and the midi generated file will be incorrect.

Maybe a simple \include with another file would be ok?


Thank you,

yohann