Classify and structure your tickets easily by assigning parent/child relationships. The parent ticket deals with the main topic and the children contain related subtopics. This way you can easily make out connections and keep an overview of relations and dependencies.
Sometimes various tickets will deal with the same topic or belong to the same project. Then you can link several tickets and assign them a parent/child relationship.
Here's a possible use case:
Imagine that you are hiring for an open position. You could create an internal parent ticket that describes the role, e.g. "Graphic Designer Position". Every ticket you receive with an application can then be linked as a child ticket of "Graphic Designer Position". This way they are all grouped and classified in a logical and easy way.
So as you can see, the idea is that the parent ticket handles the main issue or topic. Child tickets address all corresponding subtopics. The idea is to create a hierarchy and a better overview.
Parents and children can be assigned to different agents, or to the same person - just like normal tickets.