Graft coupling between two reactive polymers can lead to the formation of compatibilized blends. There is a need to control the extent of graft coupling if the grafting system is capable of gelation, not just for the control of phase size and morphology, which depend on the amount and structures of graft copolymers in a ternary blend. In this paper, we give a thorough analysis of the molecular characteristics of the grafting system of two reactive polymers each having a large number of reactive groups. A kinetic approach is employed to quantify the molecular characteristics : concentration of individual species, molecular-weight averages and gel point. It is found that the percentage conversions of the reactive polymers to copolymers are quite limited in order to avoid a weight-average molecular weight of the system that is too high. The presence of a high-molecular-weight tail in the polydisperse reactive polymers further limits the extent of the grafting reaction, an undesirable factor in such a grafting system.