Thanks for your response, ruscon2006-gmail.

At the moment, inventory assembly is not available yet in QuickBooks Online. As a workaround, you can use bundle feature. A bundle is a group of items that you sell and track together in QuickBooks.

Here's how to add a bundle item:

1. Go to Gear icon and select Products and Services.
2. Select New.
3. Select Bundle.
4. Enter Name and select Product/Service you would like to add on the bundle and enter Quantity.
5. Select Save and Close.

Inventory items you've included on the bundle will reduce once you create an invoice or sales receipt in QuickBooks Online.

For more detailed information, you can check this article: Add product and service items to QuickBooks Online.

Feel free to post again if you have any other questions. I'll be around to help.