Thanks, Mark. This does work for a single language. What I failed to mention is that the above project is a diglot with a source (Secondary) and a target (Primary) language. Applying the code, each chapter starts on an even page in the PDF. It looks like an unnecessary blank page is added before the first chapter. I've tried adding the script to just the Primary project and also to both the Primary and the Secondary project. No change.
I should also note that \there is a \cl before \c 1.
On a side note, is there a way to exclude \c 1 so that the first chapter starts on the same page as the book title?