Can I add an invoice to a new porject? I have exisiting invoices that I would like to add to a project I just created.

Hi alln6,

Quickbooks Online makes it easy to add projects to existing invoices. To do this, simply open up the invoice in questions, click the Customer drop down and locate the project. I've attached a screenshot below for reference. Once you located the project you can select it and Save once everything looks good to you. 

Give this a try and let me know what happens. I'll be on standby.