GrandStaff questions

[Fulko van Westrenen]

;
Hello Lilypond experts,

I'm stumbling over a problem I cannot fix. Because lilypond can set
such complex music, typesetting music exactly the way you want turns
out to be rather complex.

At the moment I want to set a piece of music that has four melody
lines on two beams (treble and bass). The first melody (also on top),
is also the melody of the lyrics. I want the lyrics between the two
beams.

The problem I have is that the placement of the lyrics reacts to
melody One and Two on the treble-beam. I want the lyrics only react on
melody One. Can that be done?

How do I make TextA follow melodyA?
Is it possible to do the same with a TextB and melodyB?
Is it possible to set (parts) of the lyrics in boldface?

All with the layout:
top beam (with two melodies)
lyrics (possibly two)
lower beam (with two melodies)
(more lyrics...)


The code looks like this:
(I removed some layout from the code)

[ all actual melodies and lyrics ]

\score {
    \context GrandStaff \notes
    <
        \simultaneous {
            \addlyrics
            \context Staff =upper 
            <
                \clef treble
                \context Voice=one {\voiceOne  \melodyA}
                \context Voice=two {\voiceTwo  \melodyB}
            >

            \context Lyrics=TextA
            <
                \textA
            >

            \context Staff =lower
            <
                \clef bass
                \context Voice=three {\voiceOne \melodyC}
                \context Voice=four {\voiceTwo \melodyD}
            >       
        }
    >
}


Thank a lot,

Fulko