My father is deceased, I believe that the young lady that was living with him forged her name on his pension benefits. she's now receiving his pension

I'm sorry to hear about this situation.  It's sadly something that we see all the time.  Your chances depend on a variety of factors.  How long ago did your father pass away and how long has it been since you've known about the change to his pension benefits?  If too much time has passed, you may have lost your opportunity to file a claim.  Did your father have a will or was there an estate administration proceeding opened following his death?  You'd have to open an estate in order to raise a claim against the current beneficiary becasue the money, if the transaction was undone the money would probably have to be paid to the estate and then distributed according to his will or, in the absence of a will, the law of intestate succession.  Finally it will be important to know all about his congnitive condition at the time of the pension change and whether the lady had a power of attorney over him.  Did she sign or did he sign?  Those details will be important to know and you may not be able to investigate them before opening an estate.  You should seek out an attorney who litigates in orhpan's court regularly.  If you're in the Pittsburgh region, I invite you to contact my law firm.