Writing transformation rules is a complex task due to navigation constraints. Relaxing these constraints for the transformation time eases the rules conception. It may also be necessary, for example to transform or to use graphical editor, to add features into domain metamodels. However, these features additions as well as the relaxation of the navigation constraints must be contained in a well defined context in order to authorize exchange of models between tools manipulating several variants of the same domain metamodel. In this article, we introduce the concept of morph that corresponds to a variant of the original domain metamodel and the concept of gene that specifies these variations. The notion of morph insures the interoperability of models. We also show how to perform these morph. An experimentation with EMF is also described