The girls testimony is factually worthless.
First off, it's impossible to say what actually made her upset all the time. Depression and rebelliousness is common in 14-16 year old girls, and there have been MANY cases of molestation accusations being made by troubled girls who were simply looking for attention. This is especially common when there isn't a father in the home.
Once the mother snapped and killed the guy, the girls testimony became heavily biased. If she admitted that she lied, her mother would have been sent to prison for life for murdering an innocent man. No matter what the truth was, she was going to say that he did it. That makes her testimony worthless when evaluating the facts of the case.
There's only one living person who really knows what happened, and who could answer the question with minimal bias...and that's the cousin. The cousin knows the truth, so I'm curious why we haven't heard his side of the story yet.
Have you read the articles? There were other accusations and testimonies. I suspect that you are projecting your motives on the girl: the behavior you are displaying is what you are ascribing to the daughter.