They are doing that because they are newbies, and so they're low on the pecking order. When you introduce new chickens to a flock, the established birds can be so darned mean! I would just go and put them both inside at night if the weather get bad. Hopefully things will settle down and they'll start using the coop.
You might want to make sure they're getting enough food and water. It's just the natural way of chickens. They're very territorial, and they can even kill a newbie.....it's the one thing I dislike about chickens.
If you have room, can you put a smaller cage inside the coop for night time? That way, in the morning, the others can get used to seeing them in there, but they won't be able to hurt them, and if you put food and water in the smaller cage, it guarantees they'll be getting the food they need.
Let me know how it goes! Good luck!
Sharon
