Though Casey Johnson's passing is no doubt a tragedy, the 30-year-old heiress' untimely death did serve to reunite childhood friends Paris Hilton and Nicole Richie, who attended a private memorial at Nicky Hilton's LA house on Jan. 5. "On such a sad day it brought a smile to my face to at least have one dear friend back in my life," Paris tells Life & Style. "With my traveling, I haven't seen Nicole in a long time, and she's been so busy with having her two babies."

The former Simple Life stars, both 28, were girlhood pals who had an infamous falling-out in 2005 -- reportedly over a betrayal by Nicole that was never disclosed. Though the socialites have been in sporadic contact since, a friend close to the girls says it took tragedy to re-seal their bond. "Casey would be happy to know that even in this tragedy, she brought these friends back together," says the insider. "Like any best friends, people can get in an argument. But at the end of the day, they love each other, and that's what matters most."

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