Communication: A link between metal vacancy sites and magnetic ordering in the ion exchange intercalates of MnPS3 has been established. High-temperature X-ray patterns show that the formation of a metal vacancy superstructure and the transition to the magnetically ordered state are intimately linked, providing strong evidence that spontaneous magnetization results from the imbalance of spins on the two sublattices of the antiferromagnetically ordered host lattice leading to net ferrimagnetism.