  We observe a Quantum Brownian Motion (QBM) Model Universe in conjunction with
recently established Entanglement Relativity and Parallel Occurrence of
Decoherence. The Parallel Occurrence of Decoherence establishes the
simultaneous occurrence of decoherence for two mutually irreducible structures
(decomposition into subsystems) of the total QBM model universe. First we find
that Everett world branching for one structure excludes branching for the
alternate structure and in order to reconcile this situation branching cannot
be allowed for either of the structures considered. Second, we observe the
non-existence of a third, "emergent structure", that could approximate both
structures and also be allowed to branch. Ultimately we find unless
world-branching requires additional criteria or conditions, or there is a
privileged structure, that we provide a valid model that cannot be properly
described by the Everett Interpretation of Quantum Mechanics.
