Any system of consequence is constructed from smaller subsystems, which are interconnected.
Melvin E. Conway, 1968. Conway's Law (better stated as Conway's Conjecture) was an early concept about the complexity is systems and emergent behavior.
There has been mention that Scrum-of-Scrums is a way to scale Scrum to larger projects. And the Scrum-of-Scrums is similar to System-of-Systems.
Here's a good starting point for the concept of a System-of-Systems.
There are "some" similarities, but when you get to page 16 you'll start to see that the coordination, inter-system dependencies, and the coupling and cohesion issues overwhelm many of the simple (and sometimes simple minded) approaches to parallel Scrums.
For those trying to re-define complicated and complex this tutorial should provide some guidance that these definitions are already in place, well defined by the Systems Engineering community and should be examined before applying yet another "version" of management.
Notice to that the "emergent" behavior is well studied in the SoS world. Again "been there, done that," so no need to take credit for a new discovery. One source of this work is the seminal work starts with SysML Strategies to Characterize and Analyze System of Systems. Here is the book that must be on any bookshelf of those claiming to have opinions of complex adaptive systems - The Art of Systems Architecting, 2nd Edition. Jurgen has a straight forward map of the differences between complex and chaos. The Northwestern Institute on Complex Systems has all the backup material.
But all this tells us is that simply having multiple Scrums working on multiple threads in the project may be necessary but is far from sufficient for success. Much more is needed to control, coordinate, and define the processes between and among these parallel work elements. I hear all the advice, but I'd like to see tangible evidence that this can be applied on real projects, where real complexity is emerging. On those projects that we work, where this is the case, and we're spending other peoples money (the government's money), there is much more complexity around "program controls" than any Scrum advocate is likely to want to participate in.