Simultaneous rehearsal marks?

[David Stocker]

I need to display two rehearsal marks over the same bar line, with one 
occurring over the other. I like using the \mark command because when I 
compile the score from parts, the appropriate marks display only over 
the uppermost staff, the way I like. Is there a way to do this without a 
lot of fuss? See code below.

Thanks,

Dave

%%begin snippet


\version "2.12"

textToCoda = {
 \once
 \override Score.RehearsalMark #'self-alignment-X = #0.770
 \mark
 \markup
 \line
 \general-align #Y #CENTER {
   \small
   \bold
   \italic "To Coda  "
   \musicglyph #"scripts.coda"
 }
}

segnoSegnoB = {
 \mark
 \markup
 \line
 \general-align #Y #CENTER {
   \musicglyph #"scripts.segno"
   \hspace #0.125
   \musicglyph #"scripts.segno"
   \hspace #0.125 {
     \box "B"
   }
 }
}

\relative c' {
 \repeat unfold 4 {
   c4 c c c
 }
 %\textToCoda
%%I need both of these to display, with the to coda direction situated 
above the segno/rehearsal mark
 \segnoSegnoB
 \repeat unfold 4 {
   c4 c c c
 }
}

%%end snippet