In this paper we argue that actor-centered models are well suited for sociotechnical systems of systems (like enterprise and especially cross-enterprise scenarios). Results can especially be drawn from the field of multi-agent system modeling. However, existing approaches reveal a lack of possibilities for switching between different levels of abstraction. This does not only concern more or less abstract models for a given situation (model abstraction), but also to have models with actors of varying granularity, including individual as well as collective actors (actor abstraction). We present a modeling approach that addresses both these aspects. It is based on the core concepts of actors and activities and especially the concept of a collective actor is emphasized. For supporting different levels of model abstraction, we present multiple modeling techniques. The semantic core of all models is based on high-level Petri nets, although this is hidden for the more abstract models.