Hi Niclaos
You can embed a story map into another story map. For example you can embed another story into a Cascade so it becomes content in your Cascade story. See this FAQ for more info: Frequently Asked Questions | Story Maps
If you are a developer or work with one, you could also download the source code for our apps and customize it to add additional functionality to try and present info the way you describe, but that would be quite involved.
I think in general we'd recommend not attempting to combine too many different user interfaces in one story. For example if a reader is scrolling through a Cascade story, they may be confused to suddenly come across a story embedded in that Cascade that works a different way. So we'd advise to not over-user embedded stories. Embedding stories in stories can also complicate the user interface that people see on mobile devices. because those stories will each have their own responsive layout on mobile.
If you have a lot of information to present, a better approach may be keep those stories separate and simply assemble them as links, with accompanying screenshots, on a web page or gallery. Your users would open that page or gallery and then choose which story they want to read. So in general we'd advise not to try and combine everything into one big meta-story.
Anyone else with other thoughts, please feel free to post here.
Rupert
