Automation is an important issue in computer-aided design systems. One of the most important issues in achieving such an objective is an appropriate knowledge representation. Graphs and graph-based formalisms constitute a mean which allows for an effective representation of designs. On the basis of graphs representing the structure (static) of the design, graph grammars are a tool allowing to represent the dynamics of the design process. In this paper, we present an approach to the synchronisation of different aspects within the design process carried out by different and independent transformation systems supporting different aspects of the design. Such a synchronisation is required every time one of the systems tries to modify an area shared with the other one. The proposed mechanism is illustrated by an example of successful synchronisation in shared areas or on shared elements of the object being designed. The objective has been achieved by using different representations at different layers of the design.