Anchor point for slurs

[Oscar van Eijk]

Hi All,

I'm trying to find a way to let a (phrasing) slur that started in single
voice mode, end immediately after a multivoice part ended, as in:

\version "2.11.41"
<<
  \relative c' {
    c8\( d e f g a b c 
    <<
      { d c b a g fis g a } \\
      { g,2 b }
    >> { \hideNotes b\) \unHideNotes }
    <d b'>1
  }
>>      
\layout{
  ragged-right = ##t
}

The only option I found is using (un)hideNotes to define an anchor
point, but the hidden note does have a value, so the chord is printed
halfway the measure.

Is there a way to work around that without using control points
(http://lsr.dsi.unimi.it/LSR/Item?id=134)?

Thanks in advance,
Oscar