I need to add a sub category to a sub category

Welcome back to the QuickBooks Community, fcnewkirk. I've got steps so you can add a subcategory to a subcategory in QuickBooks Online smoothly.

To begin, I recommend going to the Product and Services page where you will find the option to manage the category. You'll then be able to perform your goal from there.

Here's how:

1. Click the Gear icon at the upper right concern and choose Product and services.
2. Click the More drop-down arrow and select Manage categorise.
3. Click the New Category button and create a new name for a category.
4. select Is a sub-category checkbox and choose the existing Sub- category.
5. Click Save.

I added screenshots below for visual references.

In case you need steps on how you can edit or remove a category in QuickBooks, you can read this article: Group products and services into different categories in QuickBooks Online.

Please let me know how else I can help you with managing subcategories in QBO. I'm more than happy to provide additional assistance, fcnewkirk. Have a good one!