I am adding my voice to the request list to be able to add a paid invoice to a project. Like other comments made, we do lots of estimates but not all turn into projects. We've been using QB for over 20 years, but just turned on the project function. We'd like to be able to do some backtracking to assign invoices to projects, even to just the beginning of this year, but I'm not going to attempt that until you announce that it can be seamlessly done without loss of transactions, links, or content.