Growing up, the Witmer sisters of New Berlin, Wis., always did everything as a trio—sports, Thanksgiving skits, impromptu singing concerts. "They didn't do anything unless it was the three of them together," says their grandmother Jan Pretzel, 64, adding that Michelle and her fraternal twin, Charity, 20, were especially close: "One would cut her hair if the other one had it long. They wanted to be individuals. But they loved each other and were joined at the hip most of the time." So it was no surprise that the twins and older sister Rachel, 24, all signed up for the National Guard, or even that, last year, all three found themselves shipped to Iraq.

They had prayed to return together too. But on April 9, during one of the worst weeks of the occupation, Michelle, traveling in a convoy in Baghdad, was killed by a bullet that hit just above the armhole of her protective vest. Two days later, her sisters brought her back to the U.S. for her funeral. At the same time, their grieving parents, John, 46, and Lori, 45, were appealing to the Guard to allow their remaining daughters to leave Iraq. "I can't live another year like I've lived this one," John told the Associated Press. "My family can't bear it."

They may not have to, thanks to a Defense Department provision that allows siblings of those killed in a hostile zone to choose whether or not to return. As of April 13, Rachel and Charity—back home on 15 days' leave—had chosen to defer that decision. "They feel they have two families, their family and their units," says National Guard Lt. Col. Mark Bruns. "They are conflicted about staying or going back."

In the meantime, the Witmers—including brothers Tim, 22, and Mark, 18—are sifting through photographs and videos and remembering Michelle, who loved to play sports and goof around for the camera; proud of her Wisconsin roots, she kept an inflatable cheese head over her bunk. But it was her caring side that one friend, Curtis Heise, now best remembers: "She seemed like someone who would work in a daycare center."

In fact, Michelle often volunteered to help disabled children at the Missionaries of Charity Orphanage in Baghdad, and the family is setting up a fund in her name to support the orphanage. "Michelle said it totally touched her life," says her grandmother. "It made her grateful for what we have here."

By Susan Schindehette. Shia Kapos in New Berlin and Lauren Comander in Chicago