Mapping of Product codes in Inter sales

Dear Gurus,

I am currently working on EPM 10 NW. The client is Textile giant. The client has its entities around the world. They have inter sales also. Now the problem is when one entity make sales with one particular code of the product to another entity it gets changed to another code of the product. For Ex:

Seller: Product Code Entity

PR011 A

PR012 A

Buyer: Product Code Entity

RS011 B

RS012 B

Both A and B are inter company entity. One more thing they are only specific product codes which are involved in inter sales. So my query is how to map the Product codes in the when this transaction takes place?

Thanks in advance.

Regards

Kumar MG