This is a little weird. The power of attorney form should identify the first, then the second and, maybe the third people in line. It does not normally allow the first to pick the second, although it may be possible. If in this case, it gives your step-father that right, then there really isn't anything you can do about it. You could sue for guardianship of your mother, but that assumes that she needs a guardian. And you would probably have to prove that your step-sister would not provide the type of care that is necessary. As far as death goes, your mother's will should identify who she wants to be her personal representative. And finally, ask yourself, is there a reason why your mother doesn't want you handling her affairs. It may be that your step-father is following your mother's wishes.
Answered on Apr 23rd, 2013 at 1:35 AM