So I revisited the first mention of Erin McKillen (the woman who is now responsible for scarring Harvey Dent) back in Two-Face's Forever Evil tie-in issue which came out one month before Erin own story kicked off in The Big Burn. Rereading this, I noticed that there was no mention of a twin sister, and that Harvey was credited for putting away "that McKillen gal," singular.
What's more, this panel indicates that she was married to a man who was the head of the McKillen crime family, whereas no such husband has shown up in The Big Burn, where we learned that she and her twin sister Shannon inherited the crime family after their father died. Again, we're talking major differences from issues set just a month or two apart.
Between this and the fact that Carrie Kelley was supposed to be at the center of this story before mysteriously vanishing without anyone raising an eyebrow, I now strongly suspect that The Big Burn was DRASTICALLY rewritten at the last minute. Erin's twin sister is so central to the plot of The Big Burn that I honestly cannot imagine how the story could have worked without her, but there's every indication here that Shannon was a later addition, so now I really want to know what the original Big Burn was supposed to be and how Carrie was supposed to have fit in!
It's honestly a bit upsetting that Harvey Dent is now being utterly redefined for the DCnU with a story that was Frankensteined together from the scraps of an earlier version at the last bloody minute.