How to get frontpage category to display sub-category posts

We’ve recently installed the Xin Magazine theme and it’s awesome. We do, however, have one slight problem. We have one category with several sub-categories, but where there are no posts in the top-category. The category in question is supposed to collect several different themes, that are seasonal or otherwise not ongoing during the entire year. It is displayed in the menu in the top as it’s supposed to be, and the posts appear in that listing when you click it. It does not, however, display the section at all on the front page, that column is just empty. How do we make it appear as it should?