You can extend your case type hierarchy by defining a parent-child relationship with existing case types. By classifying an existing case type as a child case type, you save time and effort.
In the explorer panel of Designer Studio, click Cases to open the Case Type Explorer.
Hover over a parent case type name and click .
Select Add a child case type.
Click Existing case type.
Select a case type from the list.
Caution: Review your case-type dependencies before selecting a top-level case type from the list. Demoting top-level case types can significantly alter your case instantiation process and case-type dependencies.
Click Finish.
The case type is added to your application but it does not have a life cycle or data model defined. You can define these now or at a later time.