Two mind-map notebooks with the same document?

Is it possible to have one document be changed by 2 separate minimal notebooks?

I’m in a course and create 2 notebooks, 1 for lectures and 1 for practice lessons. We have a course book and I want to reference it from both notebooks and be able to see annotations from both. The reason I created 2 notebooks is because every lesson we use different PowerPoint slides, and since there are about 13 lessons each, I would have 26 files in my document toolbar and there’s no way of organizing it as far as I know. (can’t really close documents I’m not using but did annotate in)