Reactive compatibilization constitutes on important method by which to control the size scale of phase separation in immiscible polymer blends. If a polymer pair exhibits a miscibility window at experimentally accessible temperatures, then reactive chain coupling can also be used to enhance the miscibility of the blend during spinodal decomposition in the biphasic region. We consider here the simultaneous phase separation and chemical reaction of A and B homopolymer blends in which end-functionalized A chains react with a variety of functionalized B chains to form either AB diblock, ABA triblock, or (n) over bar-armed B-g-A graft copolymers. Analytical expressions for the structure factors and Onsager kinetic coefficients are developed for each of these copolymer architectures in the kinetically controlled mean-field limit of early-stage spinodal decomposition. Multi-functional conversion-architecture-phase stability (CAPS) diagrams are introduced to facilitate comparision of the effect of copolymer architecture on reaction-driven blend miscibilization.