Hello,
In order type dependent parameters there is a configuration available to track unplanned good issues against a production order.
The suggested ways are already explained above.
The benefit of changing during confirmation is that user has 1 less transaction to execute, but there is a risk of deleting doing unnecessary changes.
Other option is to use MB1A or MIGO.
The point you should address is that why do you need unplanned goods issues in your production process ? Are the BOM;s not designed properly ?
If you need extra quantity due to rework, then you should implement a rework process. Or if you have scrapping then you should plan more in the BOM and define a scrap percentage.
Hope this helps.
Best Regards,
Ameya B.