We present the alternative way of derivation of the Wandzura-Wilczek relations between the kinematical twist-3 and twist-2 functions, parameterizing hadronic matrix element in two-photon processes $gamma^{star}pito gammapi$ and $gamma^{star}gammatopipi$. The new equations, providing the independence of the physical cross-sections on the choice of the light-cone direction, are suggested and explored. The amplitude of $gamma^{star}gammatopipi$ up to genuine twist-3 accuracy is found.
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