We discuss all contributions from inelastic SU(3)-symmetric rescattering in B decays into a final pair of pseudoscalar mesons PP = \pi \pi , K\bar {K}, \pi K. FSI-induced modifications of amplitudes obtained from the quark-line approach are described in terms of a few parameters which take care of all possible SU(3)-symmetric forms relevant for final-state interactions. Although in general it appears impossible to uniquely determine FSI effects from the combined set of all \pi \pi , K \bar {K}, and \pi K data, drawing some conclusions is feasible. In particular, it is shown that in leading order the amplitudes of strangeness-changing B decays depend on only one additional complex FSI-related parameter apart from those present in the definitions of penguin and tree amplitudes. It is also shown that joint considerations of U-spin-related \Delta  S=0 and | \Delta  S|=1 decay amplitudes are modified when non-negligible SU(3)-symmetric FSI are present. In particular, if rescattering in B⁺ \to K⁺\bar {K}⁰ is substantial, determination of the CP-violating weak angle \gamma from B⁺ \to \pi ⁺ K⁰, B⁰_d \to \pi ^-K⁺, B⁰_s \to \pi ⁺ K^-, and their CP counterparts might be susceptible to important FSI-induced corrections.

PACS numbers: 13.25.Hw, 12.15.Hh, 11.30.Hv, 12.15.Ji