how to write reaction mechanism with co-adsorption

[mingxia323]

How to write the reaction mechanism in .mkm file if the reaction species are co-adsorbed. For example, for water dissociation forming OH and H on the surface, it has species of adsorbed water (H2O*), the transition state energy (H-OH*), and the adsorbed OH and H together ((H+OH)*) on the surface. The OH and H are co-adsorbed on the same surface. How to write this reaction mechanism?