Hello there, JaneJJ.
QuickBook Desktop has an option to import your transactions by batch such as invoices. We can use the IIF file to do it. You'll have to export export the IIF file from QuickBooks and use it for reference. Then, import a different IIF file were the invoices are added.
Before that, I'd recommend creating a backup copy of your company file: Back up your QuickBooks Desktop company file.
After that, you can use this link for the step by step process on how to export and import the file: Export, import, and edit IIF files.
Aside from that, you can also look for a third-party application that can import your invoices directly to QuickBooks Desktop.
Let us know if you need anything else.