The information coupling between chemical bonds in molecular fragments, e.g., distinct parts of a single molecule or reactants in the bimolecular system, is investigated within the orbital communication theory. The relevant overlap measures of the joint/conditional “probabilities” of simultaneous two-orbital probability scatterings on different sites are established within the standard restricted Hartree-Fock (SCF LCAO MO) theory and the associated entropy/information descriptors of the chemical interactions between the bond/reactivity phenomena in such molecular subsystems are explored. The relevant four-orbital bond-projections measure the external dependencies between the associated intra-fragment communications between atomic orbitals on each fragment, thus effectively accounting for the external communication couplings between the internal chemical bonds in each subsystem.