Oh now you’ve added insults to shouting. Cute. Meanwhile out here in reality the money is legally your if you wait long enough. And given how long that it, anybody with that level of patience has morally earned the money.
Of course, if she does not cooperate in getting the money returned to her employer, in most, if not all States (certainly the 35 or so right-to-work states), she’d probably be fired as soon as the issue turned up in a reconciliation and it was determined that she did not let her employer know that she received the extra money.
The company will receive a reconcililation file, maybe paper probably electronic every month for the payroll account, which will list every check that cleared. It will contain at least a check date and check number and amount, which they can link to her payroll records. That will be all the evidence they need that she received the money.
If they’re on the ball, this will happen by the middle of November.