Outgoing, adventurous and funny, Heidi Broussard doted on her 6-year-old son, Silas, and shared updates about her pregnancy – a girl she and fiancé, Shane Carey, had already named Margo – with her wide circle of friends, posting pictures on Instagram of herself cradling her expanding belly. When she went into labour on November 26, Shane was there, as was her best friend, Magen Fieramusca, who was pregnant herself, and due around the same time as Heidi. She had travelled from Houston to hold Heidi’s hand in the delivery room while Heidi’s mum, Tammy, and father, David, raced to meet their new granddaughter in Austin, Texas. “Magen was Heidi’s friend,” says Tammy, “for a long time.”
So three weeks later, on December 12, when Heidi, 33, vanished with little Margo,…