Making a staff take extra vertical space?

[Robert Kennedy]

Without changing any other spacing, how can I make the final staff in
this lead sheet take up some extra space so the chord symbols will
move up (relative to the staff) and won't overlap the markup text?

My best idea so far is to put an invisible note somewhere (using
\transparent) at the top of the staff with its stem pointing up. But I
haven't been able to figure out how to use \stemUp; for example,
    << \stemUp f4 \stemNeutral f >>
gives me only one stem. Also, notes produced with \transparent take up
both vertical and horizontal space. I want something that takes no
horizontal space, but does take vertical space.

Thanks for any help with this!

        -- Robert

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\header{
  title = "Bouncing with Bud (Bebop in Pastel)"
  composer = "Earl Rudolph \"Bud\" Powell"
  enteredby = "Robert Kennedy"
  style = "jazz"
  tagline = ""
}

harmonies = \chordmode {
  \repeat volta 2 { bes1:maj bes1:maj b1:maj }
                  \alternative { { b1:maj } { b1:maj } }
  bes2:maj c:m7 d:m7 ees:dim7 d:m7 g:7
    c:m7 d:7 g1:m7 des:dim7 c2:m7 f:7 bes:maj b:7.11+
  bes2:maj c:m7 d:m7 ees:dim7 d:m7 g:7
    c:m7 d:7 g1:m7 des:dim7 c2:m7 f:7 bes:maj d:7
  g1:m6 g:m6 a:m7.5- d:7.9+ g:7.11+ c:7.9+ c:m7 f:7
  bes2:maj c:m7 d:m7 ees:dim7 d:m7 g:7
    c:m7 d:7 g1:m7 des:dim7 c2:m7 f:7 bes1:maj
  fis2:dim g:m6 d:7.9- g:m6 b:dim7 c:m7 b:dim7 c:m7
    f1:7.9 f2.:7.9 b8:maj bes:maj r1 r1
}

melody = \relative {
  \key bes \major
  % \override Glissando #'style = #'zigzag
  \override Glissando #'style = #'trill
  \override Glissando #'minimum-length = #5
  \repeat volta 2 { | \mark \markup{\bold "Intro"} r8 f bes[ f'~] f4. f,8 bes 
f'8~ f2 r4 r8 f,8 b[ f'~] f4. f,8 }
                  \alternative { { b8 f'~ f2 r4 } { b,8 f'~ f2 r8 ees8 } }
  { \once \override Score.RehearsalMark #'extra-offset = #'(-1 . 0.5)
    | \mark \markup { \box \bold "A1" } d c bes a c bes a g f d ees ges~ ges4 
f8 ees d c f b, r4. g'8~
    g4 ees8 c a'4 fis8 d bes' g r2 r8 a bes g r2 r8 a bes g a bes g ees d c f4 
r2 r8 ees'8
    \once \override Score.RehearsalMark #'extra-offset = #'(-1 . 0)
    | \mark \markup { \box "A2" } d a r8 c r bes r d, r a' r fis g f ees d f b, 
r2 r8 f'
    fis g ees c gis' a fis d bes' g r2 r8 a bes g r2 r8 a bes g a bes g ees d c 
f bes, r8 d f d fis g~
    | \mark \markup { \box "B" } g << g4 e d bes >> << a' fis dis c >> << bes' 
g e d >> << d'8~ bes~ g~ e~ >>
      << d'4 bes g e >> << bes'8 g e d >> << a'4 fis dis c >> << g' e d bes >> 
<< d'8~ a~ g~ ees~ >>
      << d'2~ a~ g~ ees~ >> << d'8 a g ees >> d' \times 2/3 { a g ees }
      \times 2/3 { << f'8 c bes fis >> ees' << f~ c~ bes~ fis~ >> } << f'2 c 
bes fis >> << ees'8 bes fis >> << cis'~ a~ e~ b~ >>
      << cis'2~ a~ e~ b~ >> << cis'8 a e b >> e' cis f,
      \times 2/3 { << ees' bes aes e >> des' << ees~ bes~ aes~ e~ >> } << ees'2 
bes aes e >> << des'8 bes aes e >> << d'~ bes~ g~ ees~ >>
      << d' bes g ees >> << bes'~ g~ ees~ d~ >> << bes'4 g ees d >> bes'16 a 
aes g ees8 g
      << des' e, >> << c'~ ees,~ >> << c'4 ees, >> r4 r8 ees'8
    | \mark \markup { \box "A3" } d c bes a c bes a g f d ees ges~ ges4 f8 ees 
d c f b, r4. g'8~
    g4 ees8 c a'4 fis8 d bes' g r2 r8 a bes g r2 r8 a bes g a bes g ees d c f8 
bes,
    \once \override Score.RehearsalMark #'break-visibility = 
#begin-of-line-invisible
    \once \override Score.RehearsalMark #'self-alignment-X = #right
    \once \override Score.RehearsalMark #'extra-offset = #'(6 . 0)
    \mark \markup { \bold "Fine" } r2. \bar "||"
    \once \override Score.RehearsalMark #'extra-offset = #'(12 . 0)
    | \mark \markup { \box "C" \bold "(first time only)" } c'4 c bes r8 a~ a a~ 
a g~ g4 r d' f ees r8 b~ b4 \glissando d8 c~ c4 aes8 g~ g1~ g2. b8 bes r1 r1 
\bar "|."
  }
}

\layout {
  \context { \Score \override RemoveEmptyVerticalGroup #'remove-first = ##t }
}
<<
  \new ChordNames \with {
    chordChanges = ##t
    voltaOnThisStaff = ##t
    \override VoltaBracket #'minimum-space = #0
    \override VoltaBracket #'extra-offset = #'( 0 . -1 )
    }
    {
    \harmonies
    }
  \new Staff \with {
    voltaOnThisStaff = ##f
    }
    { \melody
    }
>>

\version "2.10.14"
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