Hello,
If you want to create with reference to old sales order than you try below way.
BAPI_SALESORDER_CREATEFROMDAT2
In item structure ORDER_ITEMS_IN,
REF_DOC = 'old sales order number'
REF_DOC_IT = 'old sales order item number'
REF_DOC_CA = 'C' sales order.
If you want to create without reference than you can try as below.
1. Collect the data for the reference document with the 'BAPISDORDER_GETDETAILEDLIST' function module.
2. Create the sales document using the 'BAPI_SALESORDER_CREATEFROMDAT2' function module by transferring the prepared data.
4. Finally, you must remove a COMMIT WORK so that the sales document can be written into the database.
For this you can check below link which has example for your ref.