Not really,
Your claim cannot be supported by concrete evidence, and it is a false assumption of the concept of intelligence. Vos Savant, has a noticible talent in the verbal area, and may possibly reach an IQ level of 180 or higher. Even if she took the test numerous times her work reveals us she might have a very high intelligence.
Your sister, if she has an IQ of 156, would very likely not have the adult intelligence higher than Vos Savant in the future. In order to that to happen she would have to score on, at least, the 170 level, right now. Note that if she took an online test, the result might be highlly inflated, distorting the real results on as many as 30 points, in some cases. So, assuming she took this type of test even if just once, her IQ might be lower.
However, don't be discouraged by what you know on intelligence distribution, specialists say woomen, intelectually speaking, walk together with men in the bell curve, and maybe us, men, shiuld consider you more in this area.

Israel> the 14 year older.