Various methods of relating MSC and SDL diagrams are considered, including methods that allow one to automate manual conversion from scenarios of the behavior of the entire system (HMSC/MSC) to behavior models of separate objects (SDL), methods for supporting their conformity during the entire life cycle (concerted modification), and extensions of the MSC diagrams for real situations. The existing algorithms are reviewed, their advantages and disadvantages are considered, and our own approaches eliminating the disadvantages are proposed. The proposed algorithms are integrated into one complex.