\version "2.19.21"

\score {
  <<
    \new Staff \with {
      \consists "Timing_translator"
      \consists "Default_bar_line_engraver"
      \consists "Bar_number_engraver"
      instrumentName = "S"
      shortInstrumentName = "S"
    }
    \relative c'' {
        \time 2/4
        \repeat unfold 6 c4 
        \break
        \repeat unfold 6 c4
        \break
        R2*3
        \break
        \set Staff.currentBarNumber = #9
        \repeat unfold 6 c4
    }
  \new Staff \with {
    \consists "Timing_translator"
    \consists "Default_bar_line_engraver"
    \consists "Bar_number_engraver"
    instrumentName = "A"
    shortInstrumentName = "A"
  }
  \relative c''{
      % Suppress bar numbers by default, as this is not the top staff of the system.
      \override Staff.BarNumber.break-visibility = ##(#f #f #f)
      \time 2/4
      \repeat unfold  6 g4 
      \time 3/4
      \repeat unfold  6 g4
      % Where \RemoveEmptyStaffContext makes this the top staff, make
      % the bar numbers visible.
      \set Staff.currentBarNumber = #7
      \temporary \override Staff.BarNumber.break-visibility = ##(#f #f #t) 
      \repeat unfold  6 g4
      % and hide bar numbers again, when the upper line reappears.
      \revert Staff.BarNumber.break-visibility
      \repeat unfold  6 g4 
  }
>>
\layout {
  \context {
    \Score
    \remove "Timing_translator"
    \remove "Default_bar_line_engraver"
    }
  \context {
    \RemoveEmptyStaffContext
    }
  }
}