B^0-B ̅^0 entanglement offers a conceptual alternative to the single charged B-decay asymmetry for the measurement of the direct CP-violating ϕ_3/γ phase. With f=J/ψK_L ,J/ψK_S and g=〖(ππ)〗^0,(ρ_L ρ_L )^0 the 16 time-ordered double-decay rate intensities to (f,g) depend on the relative phase between the f- and g-decay amplitudes given by γ at tree level. Several constraining consistencies appear. An intrinsic accuracy of the method at the level of ±1° could be achievable at Belle-II with an improved determination of the penguin amplitude to g channels from existing facilities. Other non-CP eigenstates are also analysed as 〖g=D〗^- π^+,D^- ρ^+ , in those cases one has to consider together the (f,g) channel with (f,g ̅ ). We also explore B_s^0-B ̅_s^0 entangled states.