How is Expenditure Business Unit derived when Importing Project cost from PO

Summary:

I need help on understanding how the Expenditure Business Unit field is derived based on which parameters when Importing Project cost from PO

Content (please ensure you mask any confidential information):

Hi Team,

We are testing the PO cost collection process for projects. When importing costs through the Import Cost scheduled process, our understanding is that the process should be driven by the expenditure BU where the cost is charged.

Our inventory organization structure includes multiple inventory organizations, Plants 1 and 2. These are linked to a Management BU used for requisitioning, and all are linked to the US BU as the profit center.