Replenishing internal items in 11.5.10 - sourcing/display selected supplier

Hi,
Need some help/advice regarding setup for replenishing internal items to an internal inventory.

Backgound:
Item A is enabled for internal orders and assigned to both an expense - and an asset organization. Requisitions are usually placed from iProcurement. An approved BPA(X) is used for upload and maintenance of catalogue data on item A. Global sourcing rule is applied in order to allow the expense organization to be replenished from the asset organization. The asset organization is replenished from supplier using min/max-planning. All is good and well. No problem as long as also the replenishment of the asset organization for item A will be using the same supplier.