Ambitus on certain section only

[ayutheos]

I have a piece of hymn music with an intro and melody parts. I'd like to
have the ambitus shown for the melody part only. The following snippet
almost does what I want but it shows the ambitus at the end of my intro
part.


%-----8<-----snip-start---------
\version "3.16.2"

melodyIntro = \relative c' {
    \clef treble
    \key c \major
    \time 4/4
    g2 a | g2 a |
    c4 d e f | c1 \break
}

melodyI = \relative c' {
    c4 d e f g a b c | b2 c | d1
}


\score {
    <<
        \new ChordNames {
            \set chordChanges = ##t
            \transpose c ees { \override ChordName #'font-size = #1
\harmonies }
            }
        \new Staff {
            \new Voice = "intro"  \transpose c ees { \melodyIntro }
            \new Voice = "part one"  \with {\consists "Ambitus_engraver"}  
\transpose c ees { \melodyI }
        }
    >>
}

%-----8<-----snip-end-----------


How do I display the ambitus for 'melodyI' only? The time and key signatures are same for both intro and melody.


Regards,
TY