Set an existing issue as a child issue

There are two ways of setting an existing issue as a child issue.

1. On the "Show issue" page
Click "Add child issue" link below the issue detail section and choose "Add existing issue" from the menu. The selected issue on this page will become a child issue for this issue.
(If the issue is a child issue itself, the new issue will be a child issue for the same parent issue.)

2. On the "Edit issue" page
Open the "Edit issue" page by clicking "Edit" link above the issue detail section of the "Show issue" page. Click "Set parent issue" link on the top of the page, then put the parent issue key in the field.
(The parent issue must be in the same project.)

You also can choose the parent issue from the list of existing issues by pressing "Select parent issue" button.