Sales order import with price adjustment

 Hi

We have a requirement from one of our client to import sales order from external system. client requirement is price and discount being maintained in external  system  now when sales is imported in oracle  price and discount details should be also be imported(not net selling price) without maintaining pricing.

I am aware that we can have dummy price list for importing such order i am not sure by using that we can import discount details as a price adjustment. if yes, what are the setup/processing constraint are required.

Thanks in advance