Extra staves

[Ralph Little]

Hi,
I am trying to wangle the creation of a temporary extra staff that will
appear below an existing staff for the duration of the extra part only.
(Lily 2.0.1)


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I have seen the example in the tips and tricks, and the closest that I can
get to what I am after is below.

However, I am left with a couple of problems which I can't get my head
around

        * How can I easily remove the dangling clef and time sig from the
new stave? Is the only way to create a new Staff context which excludes the
engravers that I don't want, or is there an easier, neater way?

        * How can I get rid of the dangling bar line at the beginning of the
first staff, which I believe is coming from the Span_bar_engraver? I want
the bar lines to span, but not the one at the left which is not attached to
by new staff?

I've also tried entering a new StaffGroup context for the duration of the
extra staff only, but I can't seem to get continuity with the parent staff.


Any help gratefully appreciated!

Ralphy
        
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\score {
        \context StaffGroup {
                \notes {
                        \context Staff = One {c4 d e f}
                        <<
                                {c d e f}
                                \context Staff = Two {c4 d e f}
                        >>
                        c d e f
                }
        }
        \paper {
                raggedright = ##t
                \translator {
                        \StaffGroupContext
                        \remove System_start_delimiter_engraver
                }
        }
}

------8<------8<------8<------8<------8<------8<------8<------8<---

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