Hello there, trevor,

Thank you for visiting the Intuit Community.

We're unable to combine multiple invoices into a single invoice. The way you're doing it (copying and pasting old invoices into the new one), is our current workaround. You can suggest the process of combining invoices to our product engineers. Send them feedback so they'd know what works best for you. In your QBO account, click the Gear icon and select Feedback.

Feel free to reach out to me if you have other questions.