I've never done it.I wouldn't keep them in a a dog kennel.Somewhere she can run if they get into a few tussles.This also works.Put them in a cage where neither has been.So in this case neither hen will recongnize the territory.Well the old hen won't be territorial.Almsot the whole yards a chickens territory, but mainly the coop yard and the coop.Normally if hens fight its either because of no food not enough space or maybe NEW hen or just plainwn territorial.Hens shouldn't fight like that not knowing where they are or will look at eachother awkwardly.They may stay away from each other for a day or so,but once you give them treats they will be right there.In their faces.Once you see them getting social with each other put them back in there.its gonna take about 2weeks.I'd just do this.Cause my pullets were territorial.Just put them in at the same time.She may beat her if shre's been at that place longer.It will be war.Territotorial war!mines beat a HEN up.WAYYY bigger then them too.It prooves that it will turn into a disaster.I put 2 mama hens in there.The pullets were defending the first one in there.The other got beat up bAD!1st mama was a mom to all.