I'm a newbie at raising baby chicks and have a question. I've got 6 chicks (4 black sex links, 2 Leghorns) that are 4 weeks old, and today bought 2 EEs that are 1 week old. I've got them in the same crate but separated by wire and a piece of cardboard so they can't even see each other. I've got the heat lamp set up with appropriate temps for each age chick (checked with thermometer). At what age can I allow them together? I want to assure there is no damage done.