  By considering the master equation of the partially asymmetric diffusion
process on a one-dimensional lattice, the most general boundary condition (i.e.
interactions) for the multi-species reaction-diffusion processes is considered.
Resulting system has various interactions including diffusion to left and
right, two-particle interactions $A_a A_b --> A_c A_d $ and the extended
n-particle drop-push interactions to left and right. We obtain three distinct
new models. The conditions on reaction rates to ensure the solvability of the
resulting models are obtained. The two-particle conditional probabilities are
calculated exactly.
