Hi there, queencitypi!
The sub-customers will actually show up in this format: Parent: Sub-customer. If you want to see the sub-customers' names alone, we're unable to do that.
QuickBooks has reports related to customers and invoices in the Sales and customers section of the Reports page. You may want to check them out. You can also customize them to get the data you need.
Feel free to reach back out if you have other questions about QuickBooks Online.