Might be an option to take them to a park or something and be sure they would be tethered and could be taken back home again. Not that Id likely ever do that but.. Also could be a way to confine them away from certain plants while still having free range of the rest of the back yard. Would definitely need supervision though as with any tethering operation.
Dont know for the chicken its probably no worse than a hen saddle until they try to exceed the limit of the leash.
