Legal Question in Wills and Trusts in Pennsylvania

How can I or another lawyer possibly answer your question since we know nothing of the relevant facts and you do not share them? You say your father died almost 6 years ago and your sister stole money. From whom did she steal it? When? Was your father alive or dead? Who was the personal representative of his estate? You mention a lawsuit of some kind since a decision was "handed down." What was the lawsuit about? Who were the parties? What was decided? How was your sister able to gain control over your mother? Was she appointed as a guardian/conservator? if not, can you or another relative bring a guardianship proceeding? What evidence do you have either that your mother suffers from dementia and suffered from it earlier or that your sister committed perjury? Are you the personal representative of your father's estate or guardian of your mother? If so, you possibly could sue your sister although there are statute of limitations issues in your father's case. If you are talking about suing in your own right, what would your cause of action be? If the probate judge was a friend of your mother's, this should have been called to the attention of the judge and a formal request for the judge to recuse should have been made. If this was done and the judge declined, then this decision could have been appealed when the matter over which the judge presided ended, which you say was in 2014. If you did not appeal, then its going to be tough luck on your recusal claim. You cannot sit around for 2 years and then decide you should have done something about it.

There is obviously a lot more here than you relate. Since it is impossible to render competent legal advise without knowing all the facts, you are going to have to pay a probate litigation lawyer who practices in the county/state where your father's estate was or would be probated and where your mother resides and have him/her evaluate your situation and see if anything can be done at this juncture.