How to apply advance to intercompany expense invoice

We have the following business scenario; Global blanket PO has been created for A & B operating units, and the advance has been paid from A operating unit (12.2.5).

Expenses inovices have been booked under A & B operating units, as per the terms & conditions 10% of advance to be applied for expense invoices before it is paid. But the challenge is, how to apply the expense invoice to advance in B operating unit since the advance invoice has been paid from A operating unit?