Measurements of CP observables in B± → DK± and B± → Dπ± decays are presented, where D represents a superposition of D0 and $$ {\overline{D}}^0 $$ states. The D meson is reconstructed in the three-body final states $$ {K}_{\mathrm{S}}^0{K}^{\pm }{\pi}^{\mp } $$ and $$ {K}_{\mathrm{S}}^0{K}^{\mp }{\pi}^{\pm } $$ . The analysis uses samples of B mesons produced in proton-proton collisions, corresponding to an integrated luminosity of 1.0, 2.0, and 6.0 fb−1 collected with the LHCb detector at centre-of-mass energies of $$ \sqrt{s} $$ = 7, 8, and 13 TeV, respectively. These measurements are the most precise to date, and provide important input for the determination of the CKM angle γ.