A new class of heteronuclear Hartmann–Hahn experiments that is based on the simultaneous irradiation of two different multiple-pulse sequences is introduced. For these “kin” HEHAHA sequences, the scaling properties of the effective heteronuclear coupling constants are analyzed. Fourkinsequences are presented with a ratio of the active bandwidths Δν_I/Δν_S ranging between 1/2 and 1/10. The offset dependence of the polarization-transfer efficiency is examined experimentally and with the help of numerical simulations.