06/25/2013 at 09:55 AM EDT
They're already quite the sister act.
got some quality time with baby sister Gracie Elliot
last Wednesday, grinning broadly as she held the newborn, then just eight days old, in Malibu, Calif.
Gomez, 20, who was taking a lunch break from a photo shoot for her Dream Out Loud clothing line, also shared a laugh with her mom Mandy Teefey and Mandy's husband Brian.
"I'm the happiest girl in the world!" Gomez gushed on Twitter when she revealed her mom's pregnancy in May.
Gracie Elliot was born June 13. She is the first sibling for Gomez, whose parents split when she was 5. The Teefeys, who wed in 2006, were expecting a child in 2011
, but lost the baby.