Yes. One definition of "everything that exists" is "everything that exists and is connected." We can think of the universe as a directed graph and "everything

Yes. One definition of "everything that exists" is "everything that exists and is connected." We can think of the universe as a directed graph and "everything that exists" as nodes that are reachable from where we're standing. From within a sub-universe, "everything that exists" is a subset of "everything that exists" for someone standing in a containing universe. (P.S. Yes. Hi Lothar. Small world.)