Automatic Piano Reduction with > 4 parts

[Benedict Singer]

Hi all,

I'm working on a choral piece for SSATBB using 2.10, and would love to get an 
automatic piano reduction to go along with it. With 4 vocal parts this was no 
problem, but I'm not sure if it's possible in a clean way with 6. What I've 
been trying so far is essentially the following:

right hand:
\partcombine { << { \sop1 } // { \stemUp \sop2 } >> \alto }

left hand:
\partcombine { \tenor << { \stemDown \bass1 } // { \bass2 } >> }

This "works", in that it gets all 6 parts on two lines. However, things like: 
slurs, triplet brackets, etc are overlapping all over the place, since they're 
not combined between the two parts in the << { } \\ { } >> notation. 
Additionally, rests are not combined there when they can be, so if all 3 parts 
are tacet at that point, there are two rests in the piano line. Lilypond 
complains all over the place about stems and such overlapping too. I searched 
the LSR, but didn't find anything besides the current 4 part template. If the 
current approach is the only way, is there a way to do things like turn off the 
rests in one part when in the piano reduction, but not in the score, same with 
articulations, etc - besides tagging every single thing.

Thanks for any suggestions!

Ben