You can use the mouse to drag and drop periods. You can move periods to sibling or child positions in the hierarchy.
To move periods:
Highlight a period to move.
Click and drag the period to the new location in the hierarchy.
Select an option:
Move Here (Sibling) to move the period and make it a sibling of the highlighted period
Move Here (Child) to move the period and make it a child of the highlighted period
Note:
You can also copy the period as a sibling or child of the selected period. When you release the mouse button, select the Copy Here (Sibling) or Copy Here (Child) option.