staff groups.....deletable?

[Limao Luo]

I have a piece in which I have combined the violin 1 and violin 2 parts because
the notes in the first thirty or so measures are the same; however, when I try
to use the \new StaffGroup command to separate the notes into two different
staves, I find that there are three staves all in a column; however, I want to
be able to get rid of the staff they were originally combined on in the first
thirty measures. Is this at all possible?


The excerpt of code I used that produced this unwanted bug is as follows:


{
\time 7/8 d8-> (cis) b a-> (b) fis-> (g)
\new StaffGroup << \new Staff { \time 3/8 a4 e'8}  \new Staff { a (a,) e'} >>
}