Your template will be based on one single username account, based on the eBay site you are registered to - i.e. your template will be built upon your specific eBay username based on the eBay.co.uk, .com, .de, etc site. All categories, links and the shop search will be from that specific eBay country and cannot crosslink to another eBay site in another country. eBay offer no functionality for a template to dynamically change between eBay sites in different countries, they always reference back to the main site/store. The only way for you to achieve selling across multiple sites is to have a separate template for each eBay site and to list on them separately.