forcing SystemStartBracket after startStaff

[Jean-Marc LEGRAND]

Dear friends, 

I'm really stuck with this issue : I have to engrave several variations
separated by a short white space but without any line break between
them. 

Thanks to Eluze, the \markup{} trick
(http://lilypond-french-users.1298960.n2.nabble.com/Forcer-SystemStartBracket-apres-un-stopStaff-td7580894.html#none)
is OK for a single page and quite usefull. But page breaks make it
collapse...

So I'm trying to use stopStaff/startStaff and I'm stuck with the
staffGroup systemStartBracket after startStaff.

Does anyone know a magic trick such as \once \override
StaffGroup.SystemStartBracket.break-visibility = #all-visible, but
working ?

Another trick would be to change BarLine after startStaff into
something merging \bar"|" and a bracket...

Thanks for all !
JMarc


Here's a piece of code to work on : 

\version "2.17.20"

%symbol to insert in white space
two = \markup {\override #'(font-name . "Adobe Garamond Pro Bold")
\fontsize #6 "2. "} text = {\once \override TextScript.extra-offset =
#'( 0 . -7) <>-\two}

%stop and startStaff
beforeSpace = {
  \stopStaff
  \cadenzaOff
  s4 \noBreak \bar ""
}

afterSpace= {
  s1 \noBreak 
  \startStaff 
  \bar "|" s32 \cadenzaOff% Add a wee bit of staff before the clef!
  \unset Timing.measureLength
  \bar ""
   \once \override StaffGroup.KeySignature.break-visibility =
#all-visible \once \override StaffGroup.Clef.break-visibility =
#all-visible }

space = {\beforeSpace \afterSpace}

%music

global = {\key g \major \time 4/4}
 
A = \relative c'' {\repeat unfold 9 { c4 c c c } \bar "||"
                   \beforeSpace
                   \text
                   \afterSpace
                   \repeat unfold 5{c4 c c c} \bar "|."
                  }
B = \relative c' { \repeat unfold 9 { c4 c c c } \bar "||"
                   \space
                   \repeat unfold 5{c4 c c c}\bar "|."
                  }          
C = \relative c {  \clef bass \repeat unfold 9 { c4 c c c } \bar "||"
                   \space
                   \repeat unfold 5{c4 c c c}\bar "|."
                  } 
%%main

\score {
  \new StaffGroup <<
    \new Staff{\global \A}
    \new Staff{\global \B}
    \new Staff{\global \C}
  >>

}