Any BPM whose detail settings indicate it is reusable may be called by any other BPM.
To call another BPM, open the BPM you want to call it on. Drag a Call Activity to the desired map location. Open the Call Activity's properties and give it a descriptive name. Click the magnifying glass to select the Called Element from the list of reusable BPMs.
Connect the Call Activity to the other map elements with the appropriate Sequence Flows. Finish configuring the map, create all the variables the map needs, and begin mapping the BPM in the Configure tab. The Call Activity is already configured in its own BPM file. When you map the BPM that calls it, very few of its properties are available from the Configure tab.
This post is part of the BPM topic. Click here to open the BPM Overview.