Subinventory expense account

We are implementing Oracle eBS at a hospital. We are facing an accounting problem when receiving an inventory item in a expense subinventory. The expense subinventory's are all the storagerooms in the hospital, which are replenished by scanning. The replenishmentcount is creating internal orders or/and purchase orders when sourced to supplier. We have a customization for the expense account on the requisitions created by the replenishment. The account on the purchase order is the same.
When receiving a purchase order, the expense account is derived from the subinventory. This is a problem. In the storagerooms are all kinds a items stored, so it is imposible to say that all the items has to be accounted to the same cost account defined in the subinventory.