In the Administration component, on the User Management tree, open the required group.
On the Actions list, click Manage Knowledge Domains. The Manage Knowledge Domains dialog appears.
In the Available Knowledge Domains list, select the required domain then click . The Knowledge domain category is added to the Selected Knowledge Domains list.
If you select the parent category, all of its child categories are automatically added. If you do not want to include parent categories, then you can navigate to the specific category and add that on its own.