@Stan: no. Ferrets are solitary animals so we always keep them apart. All three have their own cage of two layers with hammocks and sleeping bags.
When we are at home there is Always one that is able to run free in house. And we have a 'ferretgarden' which is 8 by 4 meters, has a bamboo deck and is fenced. In there they have a small pond to swim, a large piece of ground with all kind of vegetation so they can create tunnels.