Assigning lyrics to stanzas without using \lyricsto

[Fibonacci Prower]

Hello,

I'm trying to write some lyrics to a chorus and two stanzas,
explicitly specifying the duration of each syllable (see sample file
at the end).
While trying to assign each of the stanza lyrics to the music, I find
myself on this situation:
· If I use \lyricsto, the specified durations are ignored, and the
lyrics are simply aligned to the notes.
· If I don't use \lyricsto, the stanzas' lyrics start at the beginning
instead of their correct starting point.
How can I solve that problem, then?

Thanks in advance,

-Fibo


\version "2.10.33"

bajoEstribillo = {
  e1 e2 b1 b2 e d1 f1.
  f1 d2 e d d e b1 e\breve.
}

letraEstribillo = \lyricmode {
  Si1 a2 -- brá_en1 es2 -- te bal1 -- drés1.
  man1 -- gas2 pa1 -- ra2 to -- das1 tres.1*3
}

bajoEstrofa = {
  e1 e2 b1 b2 e d1 e b2 e1 e2 b1 b2 e d1 e b2
  e1 e2 b1 b2 e d1 f f2 f1 d2 e d d e b1 e\breve.
}

letraEstrofaUno = \lyricmode {
  Tres1 mo2 -- ças1 d'a2 -- ques -- ta1 vi -- lla,2 tres1 mo2 -- ças1
d'a2 -- ques -- ta1 vi -- lla,2
  des1 -- o2 -- lla1 -- ban2 u -- na1 res1. pa1 -- ra2 man gas a to --
das1 tres.1*3
}

letraEstrofaDos = \lyricmode {
  Des1 -- o2 -- lla1 -- ban2 u -- na1 res,1. des1 -- o2 -- lla1 --
ban2 u -- na1 res,1.
  y1 fal2 -- tó1 -- les2 u -- na1 ti -- ra2 pa1 -- ra2 man gas a to --
das1 tres.1*3
}

\score {

\new Staff {
<<
\new Voice = "bajo" \relative a {
  \set Staff.instrumentName = #"Bajo"
  \clef bass
  \time 3/2
  \bajoEstribillo
  \bar "||"
  \new Voice = "estrofa" {
    \bajoEstrofa
  }
}
\new Lyrics \lyricsto bajo { \letraEstribillo }
\new Lyrics \lyricsto estrofa { \letraEstrofaUno }
\new Lyrics \lyricsto estrofa { \letraEstrofaDos }
>>
}

}


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