Topological insulators are one of the most important recent discoveries in condensed matter physics. The topological surface state can become gapped when ferromagnetic order is introduced, which gives rise to interesting quantum phenomena for example the quantum anomalous Hall effect. However, heterostructures of different materials are needed that will allow for a higher degree of control and tunability of the magnetic structure at the TI interface. Here we propose an investigation of multilayers based on Cr- and Dy-doped TI, combining the high Curie temperature of the former with the high moment of the latter, and to study interplay of crystalline anisotropy, interlayer exchange coupling and Zeeman energy. This knowlege is an essential stepping stone towards application of the topological surface state in dissipationless spin-electronics or spin-orbitronics.