BO for Build Project Analysis

I have written an External BAQ that retrieves data from another system to feed Manual Cost to Complete on the Project Cost tab of a Project. I have code within the form to pull this in, but our Finance department wants to schedule batch processing of Build Project Analysis. After each BPA is done we want to pull in the data from the external system. I can’t seem to find either the right BO or the right method that runs the actual BPA for me to put a post-processing BPM on. Does anyone know where I need to put my post-processing method to update the data after the BPA is complete?