Modularity of Reconfigurable Manufacturing System (RMS) reduces the system complexity, both in design and evaluation of the system. In this paper we proposed a modular view of the system that considers a module regarding four aspects: physical, control logic, KPI and simulation model. The last two one allows an accurate diagnosis of the system in case of disturbances. Each module is evaluated and studied. Yet, the reconfiguration decision is made regarding the system level, thus, modules have to be aggregated. The lack of aggregation methods for simulation model and control logic, and the lack of aggregation functions for KPIs constitute the issue addressed by this paper. The aim of our study is to investigate the aggregation of these aspects of the modules in order to have accurate data at the system level for reconfiguration decision making. A case study in conducted to show how aggregation could be made. Far from proposing rigid models of aggregation, the aim of the paper is to provide opportunities of thinking about the notion of aggregation of simulation models, KPI and control logic within manufacturing context, especially within modular reconfigurable manufacturing system.