You should be able to do this by using {book: true} and {book: false}.
On a line by itself, at the top of each chapter you want to include, do:
{book: true}And on a line by itself, at the top of each chapter you do not want to include in the book, do:
{book: false}If you search the Markua manual https://leanpub.com/markua/read for {book: you'll see an example of this, it's a bit hard to find, sorry about that.