Nowadays, we increasingly face the situation that possibly heterogeneous workflow environments must be integrated in order to support company-internal business processes as well as cooperation among different enterprises more effectively. Thus, interoperability of heterogeneous workflow management systems (WfMSs) is the major goal of one of our projects conducted with industrial cooperation partners. In this paper, we, on one hand, report on how our approach supports integration of heterogeneous WfMSs in general, and, on the other hand, detail the very important aspect of allowing workflow applications associated with different, possibly heterogeneous workflow environments to share product data. Traditionally, the management of product data is beyond the scope of a WfMS and is left to the individual workflow applications. However in a multi-WfMS environment, additional control facilities are needed enabling multiple and potentially different WfMSs to share data for cooperation purpose...