For pt.I see ibid., vol.2, p.7373 (1990). The first-order ferroelastic Fm3m to or from R3 structural phase transition occurring in ordered MIIZrF6 fluorides (MII=Co,Zr) is studied by means of Brillouin and Raman scattering experiments. The Brillouin data obtained with a CoZrF6 single crystal show that the elastic constant C44 does not change in the cubic phase, when the transition temperature (Tc=272+or-1 K) is approached from above. The Raman spectra of CoZrF6 and ZnZrF6 in the cubic phase are consistent with group-theoretical predictions; in the rhombohedral phase, the spectra exhibit a splitting of the nu 5 triply degenerate bending mode of the MII(Zr)F6 octahedra and show the existence of two soft rotatory modes of these octahedra. From these results and group-theoretical considerations, it is concluded that the phase transition can be considered as improper ferroelastic, driven by octahedra rotations; possibly, an intermediate behaviour between true displacing and order-disorder regimes takes place in these materials.