@JessT : Thanks for your reply. That may be fine but probably as a last resort. I am not sure if what you suggest would be correct. Given it seems how QBO is designed, I believe one would have to, in such cases, do a Credit Note for the entire item and then do a fresh invoice.

Second question: How can we get a discount field in every line item under Products/Services? Currently there is one Discount field in the bottom.