Multiple instruments in score and parts

[David Sumbler]

I am intending to set a largish project, which is written for a small
orchestra, vocal soloist and narrator.  The piece consists of a number
of short movements, and not all of the forces are required for every
movement.  I have a pretty good idea of how I am going to manage the
input files for this to produce score and parts, with "tacet" markings
in the parts for some movements.  But there is one particular area in
which I should like some suggestions or recommendations.

The 1st violins, for instance, mostly play a single line of music,
which will of course appear on a single stave in both score and parts.
 At times, though, they are divisi à2, and even occasionally à4.
 Typically I might want an à2 passage to appear on a single stave in
the score but on 2 separate staves in the parts.  The à4 passages might
be on 1 or 2 staves in the score, and 4 (or perhaps just 2) staves in
the part.

At the moment I cannot really see how to deal with this sort of
problem, other than having completely separate input for the score and
the part at these points, controlled by tags.  But is there a better
way - one which requires less duplication of material in the input?

Any suggestions or pointers to help with this will be gratefully
received!

David