I would rather be safe than sorry. Since you are new to chicken keeping, you may not have a feel yet for what the other birds might do nor know their personalities well.
Put mama and egg in a dog crate on the floor of the coop until the other birds have a chance to get use to the new little one.
Put mama and egg in a dog crate on the floor of the coop until the other birds have a chance to get use to the new little one.