adding new staff on the fly in a staff group

[Orm Finnendahl]

Hi,

 in the following example, adding a new staff on the fly within the
uppermost staff of a staff group adds the staff below the last staff
of the staff group. Is there an easy workaround to create the new
staff directly below the uppermost staff?

--
Orm

\version "2.19.5"
\score 
{ 
  <<
    \new StaffGroup
    { 
      << 
        \new Staff { c'1 << c'1 \new Staff {f' 1} >> }
        \new Staff { d'1 }
        \new Staff { e'1 }
      >>
    }
  >>
  \layout {}
  \midi {}
}