Kneed beam with polyphonic music

[Helge Kruse]

Hello,

I need to switch the staff for some purposes. To avoid clash with other 
notes I want to use a kneed beam. For this staff switch. Unfortunately I 
have also polyphonic music.

How can I enable the kneed beam for the quavers in music below?

Regards
Helge

top = \change Staff = "1"

bottom = \change Staff = "2"


% looks as it should, but don't have the voice one line.

musicA = \relative c {
  \override Beam #'auto-knee-gap = #1

  \bottom c8 g' \top e' c'

}


\score {

  \new PianoStaff <<

    \new Staff = "1" { \musicA }

    \new Staff = "2" { \clef bass s4 c }

>>

}


% following won't produce a kneed beam.

musicB = \relative c {

  \override Beam #'auto-knee-gap = #1

<<

    \new Voice { \voiceOne e''4 e }

  \\

    \new Voice { \voiceTwo \bottom c,,8 g' \top e' c' }

>>

}

\score {

  \new PianoStaff <<

    \new Staff = "1" { \musicB }

    \new Staff = "2" { \clef bass s4 c }

>>

}