To move the lamps you need to group them first or move only the base! To copy the lamp must also be grouped first. All elements except the base are locked (Hierarchy tab> Link Info> Locks).
A cool way to bring light above the dining table when a ceiling lighting fixture is not an option.
DCW Editions Lampe Gras N°214:
DCW Editions Lampe Gras N°204:
DCW Editions Lampe Gras N°411: