Confirmed qty change in Sales Order

Hi all!

Do you know if exsist a fm or bapi to modify the confirmed quantity in schedule line of a sales order?

I know that exsist BAPI_SALESORDER_CHANGE but I'm not able to modify confirmed qty.

My flow consists in two steps:

1. sales order create with confirmed qty = 0;

2. sales order change to modify confirmed qty.

Thanks,

Gianluca