Output Combined Parts

[Joshua Koo]

Hi

I put each of my instrument notes is inside a separate file, so lets say all 
cellos notes are inside cello.ly and violin notes are inside violin.ly
In each of these files, they have a \score{} so I can print out the indiviual 
parts.
Then I have a score.ly which have a huge staff which combine all the parts 
together. however, while is parsing the individual instruments like cello.ly, 
it will render the \score{} inside, causing the score.pdf not only to contain 
the combined parts, and it has the separate parts.

Is there anyway I can control when to  print the indiviual parts, and when to 
print all parts as a group?

Thanks,
Joshua