Anti-Phase Boundaries (APBs) formation in B2 (ordered Body Centered Cubic) structures was investigated, focusing on the Al-Fe-Cr/Ni alloys. The current research goal was to propose strategies for controlling APBs formation in multicomponent alloys, following their positive effect on properties of High Entropy Alloys, stated in previous researches. This study is based on our previous investigation of the APBs formation mechanisms in binary B2 Fe50+xAl50-x alloys. There, stable APBs have formed at and above specific Long-Range order parameter. Here, it was established that stabilization of APBs requires disorder at only Al sublattice. Thorough analysis of dislocations revealed that higher complexity accelerates the decrease of order, promoting the formation of APBs. An assessment of disorder in multicomponent systems is challenging and sometimes even impossible, therefore suggested here usage of evaluation of dislocations is an interesting and useful experimental tool to estimate the disorder in these complex systems.