I've got 3 9.5 week old Buff Orpington chicks. I've got them in a separate pen inside the big run with my adult BO and Jersey Giant. They've been in this set up for 3.5 weeks. And I was hoping to go a few more till the babies were a tad bigger. But they are really getting antsy and yesterday, one of the babies flew out of the separation pen and I came home to find her with with the two big hens. Amazingly, they didn't kill her. Now maybe she was only there for a few minutes but more than likely, she'd been there for several hours. So I want to integrate this weekend and I really like the idea of setting up a panic room for the babies to get away from the big hens. But how? I've tried opening their pen just 5 inches or so but the big hens can squeeze through. So I'm thinking I need to cut a pop door shape out of cardboard or wood and go that route. I'm looking for any advice or direction on size, shape, etc.