You can show diagram elements that are related to the
selected diagram element in a modeling diagram.
For example, if you created a class diagram that
illustrates a parent class and its child classes, you can add the
parent class to a new diagram, and then use the Show Related Elements
feature to add its child classes and generalization relationships
automatically.
Note: To show related diagram elements,
the model elements and relationships must already exist.
To
show related diagram elements: