Witness to a changing of a will of a grandparent

My grandmother had a massive head trauma in April 2010. My grandfather passed in May 2010 and my aunt coherced my grandmother into changing the will 5 days after we buried my grandfather. My mom passed in March 2009 which would have left her part to myself and my brothers. The changed will read that everything would to to my aunt and her youngest daughter. My aunts granddaughter (daughter of other one named in Will) witnessed the signature of my grandma. My grandma was putting reeces pieces on pizza and was not in sound mind at all. The will has already gone thru probate here in Ohio and is closed. My aunt had stated that I would be taken care of. Is there anything that I can do legally since it has been over a year since probate has closed? The attorney that did the will was also a customer of my cousin (who was named in the will) at the bank she worked at.