Create a Parent to a Current Requirement
Relation will be set up automatically once any Parent Requirement is created from a Requirement. You need not set the relation again manually.
Launch a Requirement issue
Click the "Create Parent" button from the Requirements section
Specify the information and finish the Requirement creation process
The newly created Requirement will be presented in the Requirements section as a Parent

[Screenshot - UG0006_Requirement_issue_Create_Parent]