You can be apply to be the administrator of your brother's estate.  Once appointed, you can look into and even pursue any unpaid amounts he was entitled to under the divorce decree.  These would become estate assets and be distributed to his heirs, or you if you are his sole heir.  If you need assistance in this matter, I would be happy to help you. You can contact my office at 216-378-7570 or www.socrateslegal.com .