We describe the growth and properties of (In0.5Al0.5)1-xMnxAs and (In0.5Ga0.5)1-xMnxAs epilayers and superlattices. We find that the structural quality of the epilayers is similar to that of the more extensively studied In1-xMnxAs and Ga1-xMnxAs magnetic semiconductors and that we can incorporate significantly larger amounts of Mn (∼12%) without phase segregation. Magnetization measurements indicate that the Curie temperatures of (In0.5Ga0.5)1-xMnxAs and (In0.5Al0.5)1-xMnxAs (x∼0.11) epilayers are 95 and 25 K, respectively. The Curie temperature of the (In0.5Ga0.5)1-xMnxAs/(In0.5Al0.5)1-xMnxAs superlattices decreases with the increase of the Al/(Al+Ga) ratio. We attribute this to a decreased overlap between the impurity band and the valence band because of an enhanced Mn acceptor activation energy.