Componenet availability check / ATP

Question

Dear All,
We have created a purchase Order for subcontractor who produce an assembly for our product. We have attached a Bill of material which has three to four material as an Alternate material. We have set the Alternate group , priority , strategy as 2 check for 100% availability as well as probability also based on the requirement.
When we explode the BOM from the same Purchase order / Job work order to check the Requirement. System displays the entire list of component along with the Alternative materials alongwith the Requirement as per BOM.
When we check the Component availability ( selecting from menu) , system shows the available Qty against One material and other alternate material requirement qty becomes zero.
But the problem is when we check the stock of the component / Altenate material. through MMBE , it shows zero quantity in stocks, But there is Purchase order for the original  component alternater material  of more then required qty.
Our requirement is that System should not consider the pending PO qty while doing ATP / component availabity check at the time of creating reservation for the material defined into Jobwork / Subcontractor Order.
Pending PO qty which is not received  at plant, then how the same can be used allocated to Reservation.
May tyou please let us know that what parameter we have to set into SAP system  so that system should not consider the pending po qty for availablity check.
thanks
harish

Answer 1

I have run OPJJ but in this the checking rule "02" is defined for PP - " Production Order" while running MRP.
We want to apply the checking rule for Purchase Order where we can exclude the same.
We would like to know that how can we define the new checking rule for Purchase Order and assign the same to it.
We have seen that checking rule which is showing in the ATP list of component is PP and availability check " 02".
In Checking rule " PP " and 02 , Purchase Order is included. If we remove the same then while running MRP  , system will not consider the purchase order.
let us know that how can we create new purchase rule for Purchase order.
thanks
harish