lyrics between staves & repeats

[ehzone]

I'm trying to typeset music and lyrics but I'm having troubles and I
don't know what to try next.  At one point in the piece a few measures
are repeated but with different lyrics.  I have managed to get the
first set of lyrics to print between the staves but the second set of
lyrics appears under both staves.  I want both sets of lyrics between
the staves.  I've tried to typeset it but can't get the 2nd verse to
appear between the staves.   What I tried is attached below (I
stripped away everything that I think is irrelevant but it's still
pretty long).

regards,
Eh.

\version "2.12.3"

global = {
    \key c \major
    \time 4/4
}

\parallelMusic #'( voiceA voiceB ) {
  a4 a a a   b b b b |
  a1         b1      |
  \repeat volta 2 {c4 c c c}   d d d d |
  c1         d1      |

}

% technique suggested in notation reference, 'ref
words = \lyricmode {
 eh eh eh eh | bee bee bee bee |
 << { sea sea sea sea }
    \new Lyrics
    { mi  mi  mi  mi }
 >> | d d d d
}

\paper {
  #(set-paper-size "letter")
}

\score {
  % create a new piano staff that accepts lyrics between the two staves
  \new PianoStaff \with { \accepts "Lyrics" }
  <<
    %  define the upper, or treble, staff
    \new Staff = upper
        {  \global
           % the voice will be created explicitly in order to map the lyrics
           \new Voice="first"  { \voiceOne \relative c'' \voiceA}
        }
    % attach the lyrics to the the voice named "first"
    \new Lyrics \lyricsto "first" \words

    % create the lower, or bass, staff
    \new Staff = lower
        {
           \global \clef bass
           % implicitly create the voices since nothing special has
           % to be done with them
           \relative c  \voiceB
        }
  >>

  \layout { }
}