The beneficiary(ies) on a life insurance policy are entitled to the death benefit.  The beneficiary can give his/her share to whomever he/she wants.  The death benefit passes "outside the estate" meaning it is not included in your Father's estate if there was a proper designation of beneficiary on file.  If there are questions as to the validity of the beneficiary designation - such as the fact that the beneficiary gave up the rights to the death benefit in a divorce and the form was not changed to reflect it, or that the beneficiary used some type of undue influence to get themselves named - then you can contest the death benefit designation.  You indicated that she has already collected.  You may need to see a lawyer to sort through this all if you feel and have proof that the payment was incorrect.