Business processes interoperability is an impor- tant issue for distributed applications in collaborative envi- ronments. This problem is further complicated in dynamic collaborative environments where stakeholders can quit the network and be replaced by new ones. To date, existing approaches do not provide the necessary flexibility to handle the dynamic nature of the network. In this work a formal framework is developed which combines cross-organizational process specifications with mediation-based solutions to ensure business processes interoperability. The concepts defined in this framework are used to build flexible collaboration con- tracts that better handle the dynamicity of the network. The applicability of the framework has been illustrated through a real-life industrial use-case in the aerospace industry for collaborative aircraft design process. The proposed framework provides higher level concepts than existing process modeling languages which better captures the business intent behind the collaboration