In the software and system modeling community, research on domain-specific modeling languages (DSMLs) is focused on providing technologies for developing languages and tools that allow domain experts to develop system solutions efficiently. Unfortunately, the current lack of support for explicitly relating concepts expressed in different DSMLs makes it very difficult for software and system engineers to reason about information spread across models describing different system aspects. As a particular challenge, we present in this paper how we dealt with relationships between heterogeneous behavioral models to support their concurrent and coordinated execution. This was achieved by providing dedicated metalanguage to define the behavioral semantics of DSMLs and their coordination. The approach made explicit a formal model of the control flow (MoCC); domain-specific actions (DSA) and a well-defined protocol between them (incl., mapping, feedback and callback) reified through explicit domain-specific events (DSE). The protocol is then used to infer a relevant behavioral language interface for specifying coordination patterns to be applied on conforming executable models. As a result, heterogeneous languages and their relationships can be developed in the GEMOC studio, which provides extensive support to run and debug heterogeneous models. This is outlined in the paper on the definition of the Marked Graph language and its coordination with a scenario language.