Ferroelectric structures in thin films result from the combined effects of mechanical stress induced by the substrate and electrostatic/mechanic boundary conditions at ferroelectric domain walls. In that respect the control of ferroelectricity in thin films can be achieved by using strain engineering methods, i.e. selecting suitable substrates and applying thermomechanical stresses through thermal processes. Here we aim to investigate the stress relaxation mechanisms and ferroelectric structures in GeTe thin films grown by MBE on miscut Si substrates. A 3D mapping of reciprocal space around GeTe ferroelectric Bragg peaks will be performed by GIXD to quantify the anisotropic stress relaxation state and ferroelectric domain structure. Their evolution as function of temperature and film thickness will be addressed. The role of atomic steps on stress relaxation processes and ferroelectricity will be deciphered by close comparison with GeTe thin films grown on a nominal Si substrate.