sales org change in billing document

Hello All

Customer had created sales order with sales org as HK00 and delvery has been created for the same.Now the user has chnaged the sales org in the sales order as CNOO and then billing document has been created with reference to delivery document.But the billing document has been created for sales org HKOO.Now the user wants that billing document should be created for Sales org CNOO.

Could you pls suggest a solution as all the subsequent documents have been created after delivery

Thanks in advance

Regards

T.Srikanth