Billing Document issue

Hi

In my Business Process like this sales order, Billing & Delivery

But the Problem is they want to Raise the Delivery document with reference of Billing Document is it possible in SAP?

And also one more problem is also there , once they created the billing Document and they issue the invoice to the customer

after that few days they want to change the pricing of that billing Document and they want to issue same invoice number they don't want another Invoice because its a Textile Industry and delivery is not happened ?

Regards,

Prasanna

Edited by: prasanna_sap on Mar 21, 2011 6:13 PM

Edited by: prasanna_sap on Mar 21, 2011 6:15 PM