I just posted a new thread on this subject, no noticing this one already.
As cryptic as the answer was, I find it immensely encouraging, because it clearly acknowledges the significance of the request. There are various ways of implementing this functionality, at various levels of automation (and artificial intelligence). While rules of writing for winds in scores are fairly straightforward (you write a2, or zu2 when both are playing the same line, or 1., I., 2., II. when only one is playing), in practical use, there is often room for ambiguity (such as when a two-voice melody comes to unison for a few notes, for example). For reasons of clarity, we don’t always mark these passages ‘a2’, as the common sense implies that the few notes aren’t going to be a solo 1st or 2nd. It shouldn’t be too difficult to develop some logic that would make default decisions regarding the division of voicing for multi-part staves, regardless of whether the parts were written in two separate voices, or if they are single two-note voice (as is the most common practice for symphonic scores). The algorithm would simply default the top notes to the 1st instrument, bottom to 2nd (and continue to separate for more voices), and when there are fewer simultaneous notes than voices, it would look for textual clues (‘a2’, or ‘a3’, or ‘1.’, ‘solo’, etc) to decide where to put the passage. If no clear text indications existed, it would send the passage to a default voice/voices based on built-in rules, and highlight it in colour for user to intervene, to make sure the passage is correctly designated. And those rules would perhaps suggest that a monophonic passage is ‘solo’ (or ‘1st’) if it begins and ends without more than a single note at a time (i.e. if it is monophonic throughout), and is ‘a2’ if it immediately preceeded (and/or succeeded) by a two-note harmony.
More often than not, I had produced scores (for my own use) where each wind instrument had a separate staff (flute 1, flute 2, oboe 1, oboe 2, etc), which results in a score that is rather difficult to read, but allows me to rapidly generate parts for the ensemble. In other words, I was forced to compromise: in order to generate fast output (the most critical constrain for me being time), I had to sacrifice the clarity of my own score. I am hoping that this time next year, I will no longer need to make such compromises…