How do I add an invoice to an existing project, without it changing the invoice to $0?

Hi there desnedden,

Thank you for reaching out about your invoices. QuickBooks Online is a great tool able to help you create and send invoices to your customers. I can provide some information about modifying invoices.

Indeed, if you change the client or project of an invoice, the line items on the invoice will be emptied. There isn't a way to change it while keeping the line items, so they would need to be readded. I can see that this would be a feature that you'd like to see to assist with managing your invoices. I recommend leaving feedback in the system by clicking on the Gear icon, then Feedback. The comments made in that section are taken into consideration by our developers when designing new features for the program.

If you have any other questions, feel free to reach out here.