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Selena Gomez is thanking fans following the birth of her new baby sister.  The singer tweeted on Friday that she, her mother and stepfather are "so grateful" for their well wishes.  She shared the baby's name as well, Gracie Elliot, saying that her "lil sissy" was born last Wednesday. 

The news became public however through Selena's good friend and fellow pop star Demi Lovato, who tweeted about it the next day.  Selena had announced that her mother, Mandy Teefey, was expecting just last month. 

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