If you use a Fulfillment Account, you can add an unlimited number of merchants to your account through the Extensiv Integration Management interface. Adding a merchant allows you to separate cart connections (and orders) from one another. 

Step-by-step guide

1. Click on the Merchants tab and then, click New Merchant.
2. Enter the Merchant Name.
    
3. Synchronization with WMS

• Order Delivery: (sets how often orders are sent from Integration Management  to the WMS system for this merchant)
• Shipping Confirmations: (Sets how often the Integration Management  checks the WMS for new shipments for this merchant)
• Inventory: (Sets how often Integration Management  checks the WMS for new inventory levels for this merchant)

5. WMS Settings
   
   Your WMS will likely require merchant-level credentials. Check your WMS-specific setup guide for details on how to find the credentials you need.