Min Max planning

Dear All,

We are in to service industry. Oracle standard modules are used for Procurement of spare parts but operations are handled by custom module. The job card for the requirement of spare parts is created in Custom modules.

Client wants to setup Min Max plan for Spare parts to maintain Min stocks in Inventory. How can we make Min Max engine consider the Open Job cards from custom module as demand ? is there any open interface or a way to consider these jobcards as demand for calculating Re-order qty?

Thanks