since you clearly loved the chickens you lost so much, I can't imagine you'd be able to stay detached to older chickens even without naming them. My husband wanted nothing to do with our girls in case he had to do the dirty work of culling them...he didn't want to know their names either, but I do believe he has become slightly attached to them even with the tiny amount of time he's spent with them. we got our chickens as juveniles, almost at POL, and we are very attached to them...we've lost a couple and it's been torture, and I almost threw in the towel recently because we just kept getting hit with health issues, but I don't think I would have quite as rich a life without my girls! So sorry about your loss.