IDF is an Incremental Development Framework which supports the development and the verification of UML models for reactive systems. IDF offers refinement and extension techniques allowing liveness properties to be preserved during the model developments. Here, we improve the framework in order to analyze models from a safety point of view. For this purpose, we associate IDF with the experienced tools of safety analysis based on the BIP language by translating UML models into BIP. We demonstrate on a basic example the complementarity of liveness and safety analyses.