Thanks for trying the CM Organizer! Right now it is admittedly a little difficult to set up resources to “intertwine” the way that you described. What you can do is use the division selector while scheduling to have the first book to use all the lessons you need to do until the second book’s reading should be done, then schedule the next lessons of the first book, and so on. It could look something like this:
Book 1: Chapters 1–4
Book 2: Chapter 1 (schedule to start after Book 1, Chapters 1–4)
Book 1: Chapters 5–8 (schedule to start after Book 2, Chapter 1)
Does that make sense? It’s kind of complicated to explain but if you try it out with the CM Organizer it should make sense. 🙂