Partials and upbeats

[Phil Holmes]

I have a piece of music which has 3 vocal parts and 2 piano lines (3 
voices).  It's in 2/4 and starts with an eighth note (a quaver) in the piano 
left hand, and 2 16th notes in the piano right hand.  I want to use whole 
measure rests for the vocal parts, so that they are removed from the start, 
where there is only piano music.  If I start each vocal part with:

\time 2/4  R8   |

and the top piano part with:

\time 2/4  \partial 8  ees''16 \mf  [  g''16 ]   |

then the score is produced in the way I want.  However, if I either start 
the vocal parts:

\time 2/4  \partial 8  R8   |

or I re-arrange the piano parts so that they lie above the vocal parts, then 
I get bar-line warnings:

D:/Music/Test.ly:61:1: warning: barcheck failed at: -1/8
R8   |  % 1

Is it correct that the \partial command applies to all voices below the one 
in which it is issued, and that it cannot be used with whole measure rests? 
Both of these seem counter-intuitive to me - it seems to me that (all other 
things being equal) \partial should apply to the whole score, or just the 
single voice for which it is issued, and that it should also apply to 
whole-measure rests - otherwise you can't lose "empty" vocals with an 
upbeat.

--
Phil Holmes