Selena Gomez will be welcoming a new addition to her family -- a sibling! The “Come and Get It” singer celebrated Mother’s Day with her mom, Mandy Teefey, who is expecting a child with Selena’s stepfather. “Hope all the amazing moms had a great day! I have the best momma in the world :)) I love you so much!" she posted on May 12 with a black-and-white photo of Selena holding her mother’s baby bump.