I haven't read the book, but read all the threads. Something that caught my eye was the discrepancies in Sharon's age.
Her birthdate was supposed to be Oct? 1967. (I realize this is probably made up from a tombstone a name was taken from, but bear with me...)
She was enrolled in first grade? in 1975. That would make her almost 8 years old.
She then gave birth in 1988 at the age of 17. That would place her birth at 1970, 1971.
That's a difference of 3 to 4 years. I can see how it wouldn't be so noticable later in life, but there is a big difference between say a 5 year old vs. an 8 year old, especially to the trained eyes of school faculty, who deal with kids all day, every day.
I had a theory last night before I got finished with the threads today and read about Christine Carter. I think there is a high possibility Sharon was with a good mother, the mother was killed, and Sharon was kidnapped. The reason so many years have gone by with no connection may be because even though woman is killed and child is missing, child is presumed dead, and everyone 'knows' who killed the mother. I just don't think she was sold. Considering everything she went through, she still seems, from all that I have read, reasonably well-adjusted. Michael, on the other hand, having been raised from birth with sicko Floyd, was pretty messed up by the time he made it to foster care. I just don't think Sharon would have coped as well as she did without some kind of stable foundation. I was going to suggest looking into cases where both mothers and small daughters disappeared, and daughter was never found.
I don't know if Christine will turn out to be Sharon, but I see a resemblance, and if not, I still think if her identity is ever found, it will turn out to be something like this. I think Floyd either killed her mother himself, or knew for a fact she was dead.
Lanie