Model Driven Engineering (MDE) is based on a large set of models that are used and manipulated throughout the development cycle. These models are manually or automatically produced and/or exploited using model transformations. To allow engineers to maintain the models and track their changes, recovering transformation traces is essential. In this paper, we propose an automated approach, based on multi-objective optimization, to recover transformation traces between models. Our approach takes as input a source model in the form of a set of fragments (fragments are defined using the source meta-model cardinalities and OCL constraints), and a target model. The recovered transformation traces take the form of many-to-many mappings between the constructs of the two models.