Inter company PO

Question

Hi I have two plants 1 and Plant 2 with one customer. Customer gives Plant 2 the order for a material and Plant 2 needs to issue a PO to plant 1 for this material and then the material is produced and delivered to Plant 2 and then plant 2 inventory is updated. The material is then shiped to customer, along with the billing document.
The question that I have is how to issue a PO to another plant who will the vendor be. I cannot use STO because the material is not there in that plant, it have to be produced now.
Scenario 2:
In this scenario the only diffrence is the material is directly shiped to customer from plant 1 and billing document is sent from plant 1.
What are the transactions that I use here to fully complete this process.
Please help me out.

Answer 1

This can be handled with Third party processing.
Create company 'A' as a customer to company 'B'.Company 'B' will be a vendor to company 'A'.
Create a vendor Id for Company B in Company A.
Create the inforecord and source list for the parts that wish to procure from Company B.
Create the 3PP materials in company A with item category group as BANS. This is linked to item category TAS for Order type OR in configuration
<b>Entering a Sales Order</b>
You enter a third-party item in a sales order. The system automatically creates a purchase requisition item for each third-party item in the sales order.
Whne there is a Sales Order for the 3PP item, create the Sales Order in Company A. The SO will create a line item with item category TAS. TAS will create a 3PP purchase requisition on the vendor - Company B automatically. The Item category for the PR would be 5 - Third Party.
Change the configuration required for dealing with the 3PP POs/ PRs in SPRO..path - Materials Management>Purchasing>Define External Representation of Item Categories.
The PR can be automatically converted to PO via ME59. The PO would have the delivery address of the customer. The #pp goods can be shipped directly to the customer and need not be sent to Company A.
<b>Entering a Purchase Order to Vendor</b>
The PR can be automatically converted to PO via ME59. The PO would have the delivery address of the customer. The #pp goods can be shipped directly to the customer and need not be sent to Company A.
You enter a purchase order with a third-party item with reference to the requisition third-party item.
<b>Delivering Goods to Customer</b>
The vendor supplies the goods to the customer. To document this step in the system, you can post a statistical goods receipt in Inventory Management. However, this is not compulsory.
<b>Entering a Vendor Invoice</b>
The vendor sends you an invoice. You enter the invoice receipt in Invoice Verification. The invoice receipt is necessary before a billing document can be created in SD.
Invoice can be posted in company A by from Company B. Billing to the customer can be done from company A.
<b>Creating a Billing Document for the Customer</b>
In SD, you create a billing document for the sales order. Depending on the Customizing settings (whether or not the billing-relevant indicator is set for the item category in SD), you draw up the billing document on the basis of the order quantity or on the basis of the quantity specified in the vendor invoice. If the customer is billed on the basis of the order quantity, you can create the billing document immediately after the sales order is entered. If the customer is billed on the basis of the quantity specified in the vendor invoice, you cannot create the billing document until the vendor invoice has been entered in Invoice Verification.
Please check the link
http://help.sap.com/bestpractices/BBLibrary/html/J53_IntProcCCST_EN_US.htm