[jennyjuniper]

Stacy is not a reliable source of information. She speaks when other people are talking and therefore probably misses half of what they are saying and she seems a bit of an air head, meaning that what she does hear, goes in one ear and out the other.
I'm not saying that just because Stacey didn't know about Kim doesn't mean that Nicola did, but knowing that Nicola has an insatiable appetite for celeb gossip (God forbid that she should read an actual book) she probably did know about Kim's past.