Question: Multiple `SUMMARY.md` (navigation) sections.

[Braqzen]

Context

The SUMMARY.md creates a navigation bar on the left side of the screen that becomes scroll-able when it gets too large. It may be beneficial to split up a book into multiple books or have the SUMMARY.md navigation change based on a redirect to another part of the same book.

Github pages only host 1 page afaik therefore it might be fiddly, if at all possible, to create multiple books and somehow serve them and use them via redirects.

Question

I would like to be able to change the navigation presented such that it appears that multiple books exist under 1 book i.e. I can go from one SUMMARY.md to another (and back) so that the book can be conceptually separated and keep the navigation small.

How can I structure files such that there is a "main" SUMMARY.md and these pseudo "sub-books" have their own custom navigation sections?

Note: I did realize after the fact that navigation can be folded so perhaps this issue can be closed.