We used hybrid density functional theory to investigate 50% cubic solid solutions based on Fe-doped LaGaO₃ and LaAlO₃. The supercell composed of 8 primitive cells was used. All the possible configurations of the solid solutions considering specific magnetic ordering were split into Symmetry Independent Classes (SICs). Optimized geometry, energy and electron properties were calculated for one representative structure of each class. Magnetic coupling constants were obtained using Ising model. Estimated temperature dependences of the magnetic moment demonstrated qualitatively differences for considered solid solutions.