Thanks for joining this thread, @j0yfulone. 

I'll help ensure you're able to bill your parent customer for the job.

It's possible you have set up the sub-customer as Bill this customer. This might be the reason why only the Bill To: sub-customer/job populates on the invoice. 

To help fix this, let's first review your sub-customer information. This way, you can check to see if either the Bill with parent or Bill this customer was selected. Here's how: 

1. Go to Sales from the left menu.
2. Find and open the sub-customer. 
3. Go to the Customer Details tab. 
4. Click Edit. 
5. On the Customer Information window, make sure to choose the Bill with parent on the drop-down. 
6. Make any necessary changes. Click Save.

Once done, the information will be updated. Then, let's go back in creating an invoice to see if you're able to bill your main customer for the job. 

For more information, you can check out this helpful article: How to Add a Customer or Sub-customer. 

The steps and resources above will help achieve your goal, @j0yfulone. 

Please drop me a line if you need anything else. Have a good day.