Is there anyway that the children can spend sometime with different friends or family members as a break from one another may be good and brings about self confidence.Like adults who see one another day in day out sometimes it is good to have some space/time of their own,doing their own thing.
Make it clear that swearing is not good behaviour and treats will be withdrawn if it takes place.Be sure that they are not being exposed to swearing as children repeat parrot fashion, what they here.
When they are together get them to sit calmly and introduce a game.Get them all to agree to chose one,or if they can't encourage them to take turns and ask them how they would go about playing the game nicely.This will be a good way to practice the art of co-operation.