How to Pin Desktop Clocks Together

You can arrange your desktop clocks in any order, e.g. in a vertical or horizontal line, and even overlay them one on top of another, and then pin them together so that they become one object. This is easily accomplished by right-clicking and selecting the "Pin to clock group" option for any of your desktop clocks. Clock grouping is convenient for dragging all clocks as one item, rather than each one independently.

World Clock FAQ