Can I use BAPI "BAPI_SALESORDER_CHANGE" to create an new item line on a sales order?
I read on the FM Documentation that it's possible, but there is a check into the code of the BAPI that only allows Update and Delete mode.
If the answer is No, what BAPI can I use?
yes you can use that BAPI to create a new line item. You enter the details of the material in the table ORDER_ITEM_IN and set the item number of the new line item in the ITM_NUMBER and the update flag as "I" (for insert) in ORDER_ITEM_INX.
The "U" (for update) needs to set in the ORDER_HEADER_INX so that the entire document gets updated.
In addition, make sure you have a look at the SAP Note 1079521.