I was just watching the Mother's Day episode, where they show a flashback with Bea Arthur and the actress who plays young Dorothy in the same room at the same time.
It struck me how well cast she was to play Bea at a younger age. Her bone structure, facial features, height, even her voice. I don't know how they could have found a better choice for that role. I imagine she looks much like Bea actually did when she was young. Great job, casting director!