Following article explains how to list your items from one Amazon site to another Amazon site. You can follow the same steps to list into different marketplace such as eBay.
a) Please connect your Amazon accounts from Channel Integration section and download the products into Selro inventory. Please also create listing template for the Amazon sites that you would like to list.
b) Please go to Inventory -> Channel Products and select the channel to list products from.
c) Please select the products (upto 100) at a time and click 'Add to Channels' and follow the steps to listing the items.