In Xero, locate your Settings tab in the top right corner:
And choose General Settings from the menu:
On the right hand side, under Reports, find and click on Tracking:
In Tracking, you can easily add category options for your marketplace tracking category to match your Amazon Marketplaces:
Once you have added the tracking, refresh your cache in A2X Connections:
Once you have refreshed your cache, tracking options will be available in Settings. Choose Invoice Settings
They will be available in the dropdown list:
Click on the orange button "Update Invoice Settings".
Now, when you send transactions over to Xero, settlements will be tracked by the marketplace they are from.