We've had our two chickens for a couple of weeks (we bought them after our other three were killed in a freak dog incident!). Today we bought two new ones and need to introduce them to the flock. We've had so much conflicting advice about hwo to do this ranging from "Your existing chickens are still very young, they should be fine to put straight in with them." to "You must introduce them gradually over thirty days." Please tell me your opinions and experiences. Thanks