Cordelia and Emma aren't close at all. I think it was in the New Mutants series that Emma stated that she didn't want to see her sister again after Cordy tried to manipulate her into getting into the Hellfire Club. Cordy hasn't been seen since as far as I've heard. Uh, but from the backstory, you're right. They don't go to school together or even in the same car, and seeing as how Daddy Frost has to uphold his family image to the public, I'd doubt he'd send his youngest to anywhere but the best schools or allow her to be expelled (he's manipulated school staff before). With that said, that led me to believe that Cordy was only a few years younger than Emma and in middle school (doing drugs as you pointed out). Personally, I think with her punk rebel look and the fact that she does drugs was just a way of wanting attention (and maybe some love) from her parents. Winston may have something of an invested interest in his children's lives (making sure they're not out in public trying to humiliate him), but he's hardly the most caring father. Hazel was just pretty out of it with all her prescription drugs though.

*blinks* Oh, wait. I think you may have a point there. >> Christian's the firstborn son and first appointed heir of the Frost family, but that doesn't necessarily mean that he's the oldest. Lol. I just saw "firstborn" and naturally assumed that he had been born first. Sorry. ^^; Still, from his appearance, he's a fair bit older than Cordy and Emma though. Perhaps he's closer to Adrienne in age than I thought. Regardless, I don't remember reading anything in the comics that said he had died or anything. He was taken away to a mental institution though after his apparent suicide attempt though.

The ages you mentioned do sound plausible though. I don't think Adrienne and Christian are too far apart in age.