The engineering of complex systems and systems of systems (SoS) often leads to complex and very-time consuming modelling tasks (MTs). MTs can be distributed in several autonomous and heterogeneous places, a place being a set of stakeholders and their practices. An issue is to mastering MTs while taking into account the constraints of their large complex engineering environments (LCEE). A step toward the resolution of this issue is to deeply understand and model MTs in LCEE. In this paper, we propose to characterize an LCEE as a federation of places in order to keep the capability and autonomy of each involved place, and to apply model-based system principles to modelling of MTs. The global goal is to design a formal holistic support for operation, continuous analysis and improvements/optimizations of MTs.