In the earlier studies, so far, condensed matter physicists and materials scientists have mainly explored the interesting physical properties of Ir-based double perovskites (ABB'O6) having magnetic cation at both B (= 3d TM ions) and B' (= Ir) sites. On the other hand, a few attempts have been made to study the physical properties of Ir-based double perovskites containing three magnetic elements corresponding to the A, B, and B' sites. Considering the fact that these double perovskites could show fascinating magnetic properties due to the various exchange interaction paths among three magnetic cations, we have successfully synthesized polycrystalline Nd2CoIrO6 (NCIO) and Sm2CoIrO6 (SCIO) double perovskites to study their intriguing physical properties.