I had to seperate my older chicks and 2 wk old CX because 4 wk old chicks started picking on CX. I needed to limiting feeding for CX so they didn't eat themselves to death and they couldn't have food in front all the time like other chicks. Pile ups can kill the bottom ones esp in heat. Maybe you should think about a seperate pen? I'm sure your EE would then be happy : )
I had that problem with the only batch I tried. I ordered 200 and sold most of them, kept 80 for myself. I had them in a 10 foot by 8 foot horse stall with six heat lamps spread across the stall. Instead of spreading around under all the lights, the whole lot of them would pile six or seven deep under one lamp, and the bottom layer would get crushed to death because they would just get warm and go to sleep and not get up and move when they couldn't get enough air under there. By four weeks old, they started attacking each other and all ganging up on one bird, killing it, and then ripping it apart and eating its guts.
My friend had some do that last year . . . just one pen it was really wasn't even CX just a pen of pilers! I like my CX they are slow moving . . . unless I'm later for dinner
but I don't find them particularly stupid. In fact my free ranging CX figured out that I have an outside entrance to my bedroom and that I use it every morning, so there they were every morning - only a few other pet birds have figured that out!