You can easily move items using Cut, Copy and Paste. This is particularly useful when moving an item across a large structure.
First, select the issue by clicking anywhere in the issue's row or using up/down on your keyboard. The selected row will be highlighted.
- To move the item, click the Cut button
in the toolbar. Then highlight the new location you want the item and click the Paste button 
. The original item will be placed in the row below the selected item. - To create a copy of an item, click the Copy button
. Then highlight the location you want the copy placed and click Paste . The copy will be placed beneath the highlighted item.
To paste items under the currently focused item (as its children), press Ctrl+Shift+V (Command+Shift+V).
You can also cut/copy and paste multiple issues at one time. See Selecting Multiple Items for more details.
You can include multiple copies of an issue within a structure. The issue will still only exist once in Jira, but it can appear in multiple locations throughout your structure. This can be useful if, for example, a single task affects multiple stories.