Print barline in selecte staves only

[Urs Liska]

Hi,

I'm wondering how to manage printing barlines in selected staves only, which I 
need for a music example.

I have a score that consists of several Staff and several PianoStaff instances 
(two "songs").

When in a layout block I \remove Default_bar_line_engraver from the \Score 
context, no barlines are printed anymore (expected).
When I \consist Default_bar_line_engraver to \Staff and \PianoStaff the score 
looks like the original one again (also expected).
However, now using \bar "||" has no effect anymore. What do I have to do to be 
able to manually print barlines in a given context again?

MWE:

%%%%%%%%%%%
\version "2.19.82"

one = \relative {
  c'2
  \bar "||"
  c
}

oneUp = \relative {
  c'2
  \bar "||"
  c
}

oneDown = \relative {
  c'2
  \bar "||"
  c
}

two = \relative {
  c'2 c
}

twoUp = \relative {
  c'2 c
}

twoDown = \relative {
  c'2 c
}

\score {
  <<
    \new Staff \one
    \new PianoStaff <<
      \new Staff \oneUp
      \new Staff \oneDown
    >>
    \new Staff \two
    \new PianoStaff <<
      \new Staff \twoUp
      \new Staff \twoDown
    >>
  >>
}

\layout {
  \context {
    \Score
    \remove Default_bar_line_engraver
  }
  \context {
    \PianoStaff
    \consists Default_bar_line_engraver
  }
  \context {
    \Staff
    \consists Default_bar_line_engraver
    \consists Bar_engraver
  }
}
%%%%%%%%%%%%%%%%%%%%%%%%%
Thanks
Urs