how-to break lines before grace notes

[Keith E OHara]

I hesitate to admit this, but when I noticed that explicit line-breaks before grace notes 
were failing with "should you be using bar checks?", I searched the mailing 
list archives more thoroughly than I searched the manual.  The archives had nothing 
helpful, so I made up a solution . . . which seemed somehow familiar.

The friendly advice about grace notes and bar lines, applies to line breaks as 
well :
Notation Reference 1.2.6 Special rhythmic concerns - Grace notes, Acciaccatura, 
Appoggiatura
"Staff notation . . . are also synchronized [to grace notes].  Take care when you 
mix staves with grace notes and staves without . . .  This can be remedied by inserting 
grace skips of the corresponding durations in the other staves. "

 Either put the \break s in the staff with the grace notes, or put a 
synchronizing spacer grace in the voice with the \break s.

\relative c''{
<< \new Staff { e1        \grace c16 d1 }
   \new Staff { s1 \break \grace s16 s1 }
}