Here's how to add/update inventory values in your merchant fulfilled (aka FBM) warehouse in Zentail:
- In the Catalog, search for and select the SKU for which you would like to add inventory
- if the SKU is out of stock, search the Inactive section
- Click the blue "EDIT" button
- Select "PRICE & AVAILABILITY"
- In the Availability section, add inventory to the specific warehouse where this inventory is located and shipping from.