And while sub-customers does solve the multiple customer issue (kind of), the problem is that for event tracking you don't "invoice" customers. You receive revenue for your event via ticket sales, merchandise, sponsorships, donations, in-kind donations, etc. There is no way I have seen for me to record revenue against a project without creating an "invoice". Perhaps if Intuit were to add the ability to apply payments/deposits directly to a project without needing an invoice then the project feature MIGHT be a viable option. As it stands it is a very labor intensive proposition to try and use the existing Quickbooks project feature for event tracking.