\version "2.18.0"

#(allow-volta-hook "||")

\score {
  \new Staff {
    \time 3/4       %adjust time to suit specific tunes
    \bar ".|:"

    % Part 1
    \set Score.repeatCommands = #'(start-repeat)
    \repeat unfold 4 { a4 a a }
    \set Score.repeatCommands = #'((volta "1"))
    \repeat unfold 4 { a4 a a }
    \break
    \set Score.repeatCommands = #'((volta #f) (volta "2. --1,2") end-repeat)
    \repeat unfold 4 { a4 a a }
    \bar "||"
    \set Score.repeatCommands = #'((volta #f)) 
    
    %% instead of \once \hide Score.BarLine :
    \override Score.BarLine.break-visibility = #end-of-line-invisible
    \stopStaff

    % Increasing the unfold counter will expand the staff-free space
    \repeat unfold 6 { s4 s4 s4 }
    \break
    \startStaff  % Resume bar count and show staff lines again
    % Part 2
    \set Score.repeatCommands = #'(start-repeat)
    \repeat unfold 4 { a4 a a }
    \revert Score.BarLine.break-visibility
    \set Score.repeatCommands = #'((volta "1"))
    \repeat unfold 4 {a4 a a }
    \set Score.repeatCommands = #'((volta #f) end-repeat)
  }%end staff
}%end score