Partial measures

[Georges Roux]

How grace notes can take part at start of the music?

I know that partial command does not take into account grace notes at start

\grace a8\glissando \partial 4 c8-4 c8 \bar "||" %1

Have some problem with it, how can I do that?
Thanks
Georges

\version "2.5.21"

\header {
  title = "Maria"
  subtitle = "(Gavotta)"
  composer = "Francisco Tarrega (1778-1839)"
  style = "Classical"
  copyright = "Public Domain"  
  maintainer = "Georges Roux"
  lastupdated = "2005/May/2"
  filename  = "maria.ly"
  instrument  = "Guitarre"
  }

global = {
    \clef "G_8"
    \time 2/4
    \key c \major
  }
  
midiStuff = {
  \set Staff.midiInstrument = "acoustic guitar (nylon)"
  }
  
upperVoice = \relative c'' {
  \stemUp
  \set crescendoText = \markup { \italic "rit. dolce" }
  \set crescendoSpanner = #'dashed-line
  \grace a8\glissando \partial 4 c8-4 c8 \bar "||"                              
%1
  c8-4 b16-3 (a16-1) b8-4 gis8-1 |                                              
%2
  a8 e8-1 f8-2\glissando a8-2\2 |                                               
%3
  a8\glissando-2 \grace e8-2 e8-2 f16-2 g16-4 a16-1 b16-4 |                     
%4
  <a-1 e-1>4 c16-4 (a16-1) e16-1\2 f16-2 |                                      
%5
  }

mediumVoice = \relative c' {
  \stemDown
  \partial 4
  \hideNotes a4\rest \unHideNotes \bar "||"                                     
%1  
  a8\rest <c-1 e-1>8 a8\rest <d-3\3 f-2>8 |                                     
%2
  a8\rest <a-3 c-1>8 <a-3 c-4>8 a8\rest |                                       
%3
  a4\rest <a-3 c-1>4 |                                                          
%4
  <a-3\3 c-1>4 a4\rest |                                                        
%5
}

lowerVoice = \relative c {
  \stemDown
  \partial 4
  \hideNotes a4\rest \unHideNotes \bar "||"                                     
%1
  \set fingeringOrientations = #'(left)<a-0>4 a4 |                              
%2
  a4 a4 |                                                                       
%3
  a4 \hideNotes a4 \unHideNotes |                                               
%4 
  a4 \hideNotes a4 \unHideNotes |                                               
%5
  }

Guitare = \simultaneous {
  \context Voice="upperVoice" \upperVoice
  %\context Voice="mediumVoice" \mediumVoice
  %\context Voice="lowerVoice" \lowerVoice
  }

\score {
  \context Staff="Musique" << 
    \midiStuff
    \global
    \Guitare 
    >>
  \midi { \tempo 4=72 }
  \layout {
    linewidth = 180.000 \mm
    textheight = 250.000 \mm
    }
  }
  
\paper {
    #(set-paper-size "a4")
    linewidth = 455.244096\pt
    textheight = 24.0 \cm    % for A4 paper
    %textheight = 22.2 \cm    % for Letter paper
    }