nested lilypond-book files?

[Graham Percival]

This could be a stupid (La)TeX question, rather than a stupid lilypond
question, but here goes:

Can you have nested lilypond-book files?  If so, how?

I'd like to do this:

main.lilybook:
\documentclass{blah}
\begin{document}
\include-lilypond-book{mvmt2.lilybook}
\end{document}

mvmt2.lilypbook:
\documentclss{blah}
\begin{document}
\lilypondinclude{score-2a.ly}
\lilypondinclude{score-2b.ly}
\end{document}

What should I put on the "\include-lilypond-book{}" line?

Cheers,
- Graham