same lyrics to multiple voices at once

[Wilbert Berendsen]

I want to set a simple homophonic choir piece, with 4 voices on two staffs and 
the lyrics in between. When any of the voices has a melisma, I want the text 
to align correctly (not just when the soprano has a melisma), and also 
extender lines to be drawn correctly.

To achieve this (without changing associatedVoice each and every time another 
voice has a melisma) I try to plant all voices onto each other in one voice 
and have the lyrics attach to that voice. Of course, I don't want that voice 
to print.

\version"2.11"

sop = {a'2 b'4( a')}
alt = {g'4( f') g'2}

lyr = \lyricmode { One __ Two __ }

\score { <<
  \new Staff << \sop \\ \alt >>
  \new Devnull \new Voice = devnull << \sop \alt >>
  \new Lyrics \lyricsto devnull \lyr
>> }

But alas, this does not work, because the Devnull does not want to swallow 
other contexts. But \lyricsto doesn't want to attach to a Devnull directly. 
Is there a way to print the stacked voice in a normal staff, but remove that 
staff from view?

Met vriendelijke groet,
Wilbert Berendsen

-- 
http://www.wilbertberendsen.nl/
"You must be the change you wish to see in the world."
        -- Mahatma Gandi