  Rapid chemical equilibration of antihyperons by means of the interplay
between strong annihilation on baryons and the corresponding backreactions of
multi-mesonic (fusion-type) processes in the later, hadronic stage of an
ultrarelativistic heavy ion collision will be discussed. Explicit rate
calculations for a dynamical setup are presented. At maximum SPS energies
yields of each antihyperon specie are obtained which are consistent with
chemical saturated populations of $T \approx 150-160 $ MeV. The proposed
picture supports dynamically the popular chemical freeze-out parameters
extracted within thermal models.
