Historical USD Average Cost

Hello,

I am on a project where warehouses exist in foreign countries.  They maintain a ledger in their functional currency (ARS) and a secondary ledger in USD.  The inventory is costed in ARS but also must have an historical USD cost that is used when transferring to the USD ledger.  The Historical USD cost is the original cost when items were purchased in from US sources.  The only time the USD average cost is updated is if there is a new receipt from a US source. All issues and returns are costed from the Historical USD cost required for the USD