  We perform a comprehensive and model-independent analysis for characterizing
the spin and dynamical structure of the production of a non-diagonal pair of
Majorana particles with different masses and arbitrary spins, $e^-e^+\to X_2
X_1$, followed by a sequential two-body decay, $X_2\to Z X_1$, of the heavier
particle $X_2$ into a $Z$ gauge boson and the lighter particle $X_1$ escaping
undetected at high-energy $e^+e^-$ colliders. Standard leptonic $Z$-boson
decays, $Z\to \ell^-\ell^+$ with $\ell=e$ or $\mu$, are employed for precisely
diagnosing the $Z$ polarization influenced by the production and decay
processes. Based on helicity formalism and Wick helicity rotation for
describing the correlated production-decay amplitudes and distributions, we
work out the implications on the amplitudes and distributions of discrete CP
symmetry and the Majorana condition that two particles are their own
anti-particles. For the sake of a concrete illustration, an example of this
type in the minimal supersymmetric Standard Model is investigated in detail.
