Model Driven Development (MDD) is considered as a powerful emerging paradigm for developing system software and services. MDD relies heavily on the models to generate part of the code for implementation. It is virtually inevitable that changes at the model level result in breaking the compatibility with the existing code base. The study presented in this thesis is performed in an industrial setting. Our industrial partner is involved in MDD and has experienced compatibility problems described above. The aim of this thesis is to identify the changes that can be made to UML class diagram and investigate what kind of negative impact they pose on the compatibility with already existing Java implementations. Apart from identifying possible model changes and assessing their negative impact the thesis provides suggestions and guidelines of how to perform such modifications so that their negative impact will be minimized. / +46 455-395070