We perform computer simulations to investigate the multiscale effects of a compatibilizer on A/B/C ternary blends under shear flow. Our results confirm the phase diagram predicted by spreading coefficients and reproduce the experimental observations on such systems. Study of the orientation of the interfacial and whole polymer chains reveals a new mechanism regarding the difference in the shear rheological behaviors of the uncompatibilized and compatibilized multicomponent polymer systems. We also examine the structure formation mechanism of the compatibilized multicomponent polymer blends and find that the presence of a compatibilizer hinders the dual coalescence process of the encapsulated composite droplets. This indicates a unique approach to stabilize the vesicles upon external stress.