grace notes collisions

[Robert Edge]

  I'm having trouble avoiding collisions in the following case, can anyone point
me at some relevant documentation or example code?

\version "2.10.25"


\layout{
  ragged-last = ##t
}

\score{{
  \time 2/4
  %% grace notes collide with the triplet beam here:
  gis'8[ cis''] \appoggiatura{ gis'16[ cis''] } \times 2/3 { ais'8[ gis'
\appoggiatura{ gis'16[ cis''] } ais'8~] } 

  %% if I could make the notehead for the high d invisible it would solve my
problem:
  gis'8[ cis''] \appoggiatura{ gis'16[ cis''] } \stemUp \times 2/3 { ais'8[
<gis' d''> \appoggiatura{ gis'16[ cis''] } ais'8~] } 

  %% however, this attempt to do that fails to compile:
  %%  gis'8[ cis''] \appoggiatura{ gis'16[ cis''] } \stemUp 
  %%  \times 2/3 { ais'8[ <gis' \once \override NoteHead #'transparent = ##t
d''> \appoggiatura{ gis'16[ cis''] } ais'8~] } 

}}

I'm using 2.10.25, I tried the latest testing and got the same results.