It's nice to have you in this thread, StudioMH.

In QuickBooks Online (QBO), you can have both customer and sub-customer charges to appear on the same invoice. We have two ways to get this done:

Creating a delayed charge:

1. In the left menu, click the + New button. 
2. Tap Delayed Charge. 
3. Enter the charges you want for the customer and sub-customer.

Choose the charges you want to add to the invoice:

1. In the left menu, click the + New button. 
2. Tap Invoice. 
3. Pick the customer name. 
4. Choose and put a checkmark on the charges you want to add from the list. 

For more information about this process, see this article: What does the bill with parent feature let you do on invoices?.

Don't hesitate to post again if you have other concerns. I'm here to answer them.