Can i claim my grandfathers bank money if i am a joint holder

My grandfather and my grandmother had a joint account in bank with either or survivor .after death my grandfather is my grandmother absolute oner or not ..I have 2 uncle and my father ar legal hair of my grandpa .but bank gave all the money to my grandma account .my grandma joint with me .and I withdraw cash from this account .is I cheated my uncle ? But I have legal power as my grandma joint with me either or survivor ..my grandma is paralised .and give lti .is all the process is valid at the legal point of view.thank you .