Hello thepointbookstor,

Yes, you canimport inventory items in QuickBooks Online. You can also override the existing quantity of these items. Here's how:

1. Click on the Gear icon.
2. Under Tools, choose Import Data.
3. From the list, select Products and Servics.
4. In the Import Products and Services page, select Browser button. (You can also download the sample file to see how the columns look like.)
5. Find and select the Excel file then select Open.
6. Select Next to continue.
7. Map your data. 
8. Click on Next.
9. Check the Overwrite all values for each product or service that you import with the identical name. (This can't be undone.)
10. Click on Import.

If you have any questions, please let me know. I'm here to help.