  Using the framework of the non-local light-cone expansion a systematic study
is performed for the structure of the twist-2 contributions to the virtual
Compton amplitude in polarized deep-inelastic non-forward scattering for
general nucleon spin with an additional scalar meson in the final state. A
useful kinematic parameterization allowing for appropriate triple-valued
off-forward parton distribution amplitudes is given. One-variable amplitudes
being adapted to the fixed parameters of the extended Bjorken region are
introduced by decomposing the Compton amplitude into collinear and
non-collinear components. These amplitudes obey Wandzura-Wilczek and
Callan-Gross like relations. The evolution equations for all the distribution
amplitudes are determined showing that the additional meson momentum does not
appear in the evolution kernels. The generalization to $n$ outgoing mesons is
given.
