Hi Julian2024,
From what I gather, Doreen_P's response pretty much covers your first question.
Now, for the second one, you've got a couple of options. You can tweak the price of your items when you're recreating the bill. Or, you can just go ahead and adjust the price of the line item directly on the bill without having to reverse anything. It's all about what works best for you.
If you've got any more questions or need a hand with anything else, don't hesitate to give us a shout.
If my response has answered your inquiry, please click "Accept as Solution" to assist other users find this information.
Thanks,
Genreve