WAUKESHA, Wis. — For her whole life, 67-year-old Sharon Millard was so shy she used to ask her identical twin sister to go on dates in her place in high school. But ever since Nov. 21, when Darrell Brooks allegedly plowed into dozens of people at the Waukesha Christmas parade, killing six people, including an 8-year-old boy, and injuring up to 60 others, Millard has felt compelled to speak about the atrocity she witnessed. One of the people killed was Millard’s fellow “Dancing Granny” — 79-year-old Virginia “Ginny” Sorenson — who was tossed up in the air like a rag...