Reverse-Engineering techniques are commonly used to generate or update the CAD model of a single physical object. However, the reverse engineering of a whole assembly is still very tedious and time-consuming. This is mainly due to the fact that the complete definition of the final digital mock-up relies on the integration of multiple sources of heterogeneous data, such as point clouds, images, schemes or any type of digital representations which are not yet fully supported by actual software. Thus, having new methods and tools to better process and integrate those multi-representations would speed up the reconstruction process which could therefore become adapted to the reconstruction of large mechanical assemblies such as in automotive field. This paper addresses such a difficult problem. Actually, starting from an analysis of three different use-cases, we first highlight the lack of software solutions for the considered problematic. Then, the proposed process-workflow is introduced together with the advanced mechanisms involved in the reconstruction. In our approach, the signatures of the components play a key role in the identification of the relationships and matching procedures between the heterogeneous data. This process-workflow is illustrated on an example in the automotive domain.