How to add a page inside a page (Sub page) in dashboard?

Perhaps I don’t fully understand the query or use case however each of our CX dashboards contain numerous pages. 

If your wanting to index it to have different levels of pages within the one dashboard - then no I don’t think you can group them.  However for each of our dashboards have up to 20 individual pages, and we control who see’s which page based on user permissions.  Each user can see 2-3 pages at most and each page is tailored to their role type.

To add a page, click the dashboard heading (ours says 1 of 20 next to it, or 1 of 1).  This will expand the page list on the left hand side and you have an option to “add” from this menu.  This view also depends if you have dashboard 2.0 view enabled, but did find that when this view rolled out it was less obvious to see how to add or duplicate a page as the page list is hidden by default.