Joan VanderMolen, Lyle and Erik Menendez Courtesy of Netflix/Getty Images Kitty Menéndez’s sister, Joan VanderMolen, supports Erik and Lyle Menéndez — and a rare tell-all offered a surprising glimpse into the family dynamics since the brothers’ high-profile murder trial. VanderMolen, 92, spoke with Vanity Fair on Friday, October 11, after Erik and Lyle received a…