To constitute a bar to a disclaimer, a prior acceptance must be affirmatively proved. The mere lapse of time, with or without knowledge of the interest on the part of the disclaimant, shall not constitute an acceptance.
In applying this subsection to an interest that would have devolved by reason of the exercise of a power of appointment, the person exercising the power shall be regarded as the decedent or the transferor, as the case may be.
20 Pa.C.S. § 6206