Hi there, I've got a tabblock module which shows a bunch of categories. So I get a new tab for every category that I want which is great - I want to split those categories and have sub categories within them, then I want the sub categories to be listed in the main categories tab. How do I do that? I tried "fetch items from children categories" but that didn't seem to work.

This has to do with the module's functionality and how it is capable to provide sub-categories in the way you want them. You will have to advise the module's provider for this.