Hi there B_Marcil, 

Thanks for reaching out to the Community for advice and suggestions on the best way to import payments! 

Have you heard of QuickBooks Payments? Using Payments is a great option, as you can process invoice transactions directly from your QuickBooks Online account. You wouldn't have to worry about using a third-party program to incorporate them into QuickBooks Online. 

I'd recommend exploring the Payments service for your business needs. Take a look here for more information about it: Accept payments online.

You can also take a look at this article for more details: QuickBooks Payments Deposits FAQ.

If you have any questions about Payments and QuickBooks Online, don't hesitate to ask. I'm sure other Community members will also chime in with some advice on accepting Payments in QuickBooks Online. 

Have a great day!