Need help on Item Relationship in Oracle Inventory

Dear Gurus,

We have a requirement from Client where we have Item A, Item B and Item AB where Item AB is combination of Item A and Item B.

Here the requirement is that we will create a dummy Purchase Order for Item AB in Oracle. Then item AB in the dummy PO has to be split into Item A and Item B and this separate Item A and Item B information has to be interfaced to some other external system and in the External System will create the actual PO which will be submitted to the Suppliers. The Suppliers will send the Item A and Item B separately and at the time of receiving we have to combine back this Item A and Item B into single item