You can relate tickets when you want to make your workflow more robust.

To relate a ticket to another ticket, open the desired ticket, and then click the Related Tickets sub-tab. This tab allows you to relate the open ticket to another ticket as the parent, child, related, duplicated, before, and after. Descriptions of those options are listed later in this topic. The following options are available:

Note: The Ticket name search field returns results for both the ticket number as well as the ticket summary. However, when searching by summary, it is recommended to use only one keyword at a time. If more than one keyword is entered in a way that does not exactly match the ticket summary, then no results are presented.

A parent ticket is like an umbrella which encompasses all of its child's tasks. For example, say you want to create a ticket to collect feedback on a new feature. From each feedback point that you receive, you can create a child ticket to address any associated issues. The parent ticket is like a container for all of the feedback. To act on the feedback, create child tickets for each piece of feedback that you receive. 

As you could expect, if you would like to relate two tickets without a specific parent/child or task/subtask relationship, you can simply add a ticket with the related relationship.

If you and a teammate accidentally each create tickets for an identical issue or task, you can mark one of the tickets as duplicated.

Do you prefer to organize your tickets in the order that they need to be completed? Then you can relate your tickets to each other chronologically using before and after. For example, if task X must be completed before task Y can be completed, then X should be marked as before and Y Should be marked as after.