multiple time sigs

[address@hidden]

I'm setting a piece in which the staves do not always have the same time 
signature.  In the manual I found the \layout block below which almost solves 
my problem.  In my example here, when the outer staves have synchronous bar 
lines they cut through the middle staff.  This occurs when outer staves are in 
sync but not inner ones.  How can I prevent that while still getting the common 
bar line when all staves are in sync as in the last measure in my example?

-David

%%%%%
\version "2.18.0"

one = \relative c' {
  \time 3/4
  c2. c c c 
  \time 6/4
  c1.
}

two = \relative c' {
  \time 4/4
  c1 c c
  \time 6/4
  c1.
}

three = \relative c' {
  \time 3/4
  c2. c c c 
  \time 6/4
  c1.
}

\score {
  \relative c {
    \context StaffGroup <<
      \one
      \two
      \three
    >>
  }
  \layout {
    \context {
      \Score
      \remove "Timing_translator"
      \remove "Default_bar_line_engraver"
    }
    \context {
      \Staff
      \consists "Timing_translator"
      \consists "Default_bar_line_engraver"
    }
  }
}
%%%%%