You’ll never get this one, because the girl isn’t famous. She was famous for a while, but only in Vaudeville, and she appeared in only one noteworthy movie. The picture above is from the 1930’s.
Brother-sister dance acts were once popular. Fred Astaire danced with his sister, before teaming up with Ginger Rogers. This woman also danced with her brother, who went on to greater fame, but not as a dancer. The picture below is from the 1950’s.
It isnt’ Berniece Miracle, Marilyn’s half-sister, because I looked that up. The woman in the second picture certainly LOOKS like Marilyn, but it’s not even her mother Gladys Baker. If it’s Marilyn, that’s not a good picture of her. The jawline is too big.