In a Web service world, the Web Services Business Process Execution Language (WS-BPEL) is the standard used to compose Web services into business processes. These processes are often long-running. Therefore WS-BPEL employs a long-running transaction model to handle the internal transactions of a WS-BPEL process. WS-Business Activity (WS-BA) is a set of mechanisms and protocols to coordinate a set of Web Services into a long-running compensation-based transaction. Up to now, it was not possible to let parts of a WS-BPEL process participate in a WS-BA coordination. We show how WS-BA needs to be extended to allow parts of a WS-BPEL process to participate in a WS-BA coordination, which is supervised by an external coordinator. In addition our approach allows external partners to participate in these modified internal WS-BA transactions initiated by a WS-BPEL process and also allows for easy incorporation of BPEL sub-processes into the proposed coordination model. The architecture of a prototype implementing our approach is sketched.