I completely understand how inconvenient and frustrating this situation must be for you, drew1.

Since QuickBooks Point of Sale (QB POS) was already discontinued last October 3, 2023, there's no more option to use another payment processor in the program since it will no longer receive security patch updates and Payments and Connected Services.

Furthermore, Intuit has joined Shopify to provide an up-to-date retail solution that seamlessly integrates with QBDT Financial Software. And you're correct in pointing out that Shopify does not support assembly quantities. In this case, you can explore third-party apps in the Shopify App Store to find a suitable solution for your business.

Also, the Store Exchange will not be available using the Intuit Service. Thus, you can use any of the other four methods to exchange data between the stores: Desktop email, Web-based email, Removable Media, and Network file transfer. Refer to this article for more details about this process: Store Exchange Overview.

Though you can use the QB POS software until you find another POS system, please remember that Intuit will no longer support the product. Please visit this article for detailed information about this process: QuickBooks Desktop Point of Sale discontinuation.

If you want to learn more about how to share information between QuickBooks POS and QBDT, check out this article: Financial Exchange Overview.

Please don't hesitate to post again or comment below if you have clarifications about the discontinuation of QuickBooks POS. We'll always be around to assist you.