I'm glad to see you here in the Community, @JP323.
For now, we're unable to add the Quantity Available column on the sales order. You may consider turning on the warning if there isn't sufficient stock to sell. This way, you'll know when the quantity you want to sell exceeds the Quantity Available.
Here's how:
- Go to Edit and select Preferences.
- Select the Items & Inventory tab.
- Choose Company Preferences.
- Select the Warn if not enough inventory to sell checkbox.
- Choose When the quantity you want to sell exceeds the Quantity Available.
- Click OK.

You can also utilize the Sales Order Fulfillment worksheet to help you track the sales order fulfillment process. Beforehand, ensure you have turned on the appropriate Advanced Inventory preference. I'll show you how.
- Repeat steps 1 through 3 above.
- Select the Advanced Inventory Settings button.
- Go to the Site Operations tab.
- Check the Sales Order Fulfillment Worksheet box.
- Click OK.


Once done, refer to this article to start managing your sales order: Fulfill a Sales Order using Advanced Inventory.
Please let us know if you have other questions or concerns. We're always around to help. Have a good one.