You need to retain a probate attorney. The niece has a high bar to over come that she was incompetent to make her last will and testimony. If she prevails, then the previous will come into play. If she is not listed as a beneficiary, she would get nothing. If there is no other prior will, ten your stepmother dies intestate (without a will) and state statue would define how the estate is distributed. As a niece, she is very low in the order of distribution.
Answered on Feb 11th, 2014 at 3:22 PM