what's the best practice to maintain standard cost on the Trade Org on Global PO?

Summary:

Our customer is located in US(US USD BU), and is procuring goods from suppliers in China through an internal trading company located in Singapore(SG USD BU), which charges 20% PO amount markups against US headquarters(This has been set up on the pricing rule on the financial orchestration and in cost component mapping group we mapped the transfer_price with an overhead called 'Markup'), now customer uses standard costing method in system, the cost valuation unit is setup at cost org(same with BU) level.

Under this scenario, we are preparing to use Global PO and calculate the markup amount using financial orchestration.