In previous work, molecular dynamics simulations based on a first-principles-derived effective Hamiltonian for (PSN), with nearest-neighbor Pb-O divacancy pairs, was used to calculate vs. T, phase diagrams for PSN with: ideal rock-salt type chemical order; nanoscale chemical short-range order; and random chemical disorder. Here, we show that the phase diagrams should include additional regions in which a glassy relaxor-phase (or state) is predicted. With respect to phase diagram topology, these results strongly support the analogy between relaxors and magnetic spin-glass-systems.