One notebook for several mindmaps

Dear Margin Note Community,
I have been using MarginNote for a couple of years now (lightly) and starting to intensify my use. As I am rather at the beginning of a intensive literature review, I would like to make the most of it and I have one particular problem in my workflow I seem not to find a solution for online.

My setup: I have included a lot of different research articles into one Mindmap Notebook.
My plan: I would like to start a new Mindmap Notebook and work with a subset of the articles.
My problem: Unfortunately I do not see the old excerpts as MN uses a different/new layer in the document view.
Is it possible to use the same “layer/document” in different mindmap notebooks? I do not want to look for the important parts of the text all over again.

I hope you can point me in the right direction, either with an actual option how to do so or with a hint for the improvement of my workflow/setup logic to workaround.



Kind Regards,
Support Team