Model transformation is one of the key principles of Model Driven Engineering. Many approaches have been proposed to design and realize them. However, for all the approaches, model transformations are considered as single entities that can only be chained if their input and output metamodels are compatible. This approach has the major drawback to focus on the satisfaction of the compliance property when building a transformation chain. In this paper we propose a mechanism for combining independent model transformations which jointly work towards a common objective but do not initially handle compatible metamodels. Our proposal is independent of any model transformation approach. It has been validated using Gaspard, an environment dedicated to code generation for embedded systems.