Thank you for contacting us, WildWellLLC.

You can only merge accounts, customers, and vendors. That's why you're getting an unexpected error when performing this process on your inventory items.

Please refer to this article for additional information: How to merge accounts, customers, and vendors. It will guide you through the process of merging the information I've mentioned above.

There's a feature where you can group your products and services in QuickBooks Online. Simply categorize them to keep things organized.

Let me show you how:

1. Select Sales from the left navigation bar.
2. Go to the Products and Services tab.
3. Click the More ▼ drop-down menu, then select Manage categories.
   
4. Hit New category, then enter a unique name for this group.
5. Click Save.

I've added this link for more details: Group your products and services into different categories. This article will tell you more about grouping your products and services.

Keep me posted if there's anything else you need about the process above. I'm always around to help you out.