Model Transformation is a software engineering mechanism for transforming one model into another model between different phases to develop a software system. A metamodel defines the abstract syntax of models and the interrelationships between model elements. Model transformation approaches use different metamodels to represent source and target model of the system. This paper investigates for a unified metamodel when they share set of core representations in different phases and checks the possibilities for multidirectional transformation for code generation, upgradation and migration purposes.