Celebrity Parents Beyoncé and JAY-Z Worried Blue Would Feel 'Left Out' After Twins' Birth: Source The "Formation" singer "made sure to spend lots of quality time" before welcoming twins, says a source By Melody Chiu Melody Chiu Instagram Twitter Melody Chiu is a Senior Editor for PEOPLE. She has been with the brand since 2009, editing, writing and reporting across all entertainment verticals. She oversees PEOPLE's music and events coverage and has written cover stories on Taylor Swift, Selena Gomez, Melissa McCarthy, Blake Shelton and Sandra Oh. The Los Angeles native graduated from the University of Southern California and has appeared on Extra!, The Talk, Access Hollywood and Good Morning America. People Editorial Guidelines Published on August 23, 2017 09:00AM EDT Share Tweet Pin Email Blue Ivy is one happy big sister. Before welcoming twins Sir and Rumi on June 13, Beyoncé, 35, and JAY-Z, 47, were worried their 5-year-old daughter would “feel left out,” but the toddler has completely bonded with her siblings, a source tells PEOPLE exclusively. “Beyoncé has been very busy with the newborns, but she’s also been able to relax a bit. It’s helped her that Blue has been such an amazing big sister,” adds the source. Before the babies arrived, the new mom of three “made sure to spend lots of quality time” with Blue. For all the details on JAY-Z and Beyoncé’s new mansion and their plans for their family, pick up the latest issue of PEOPLE magazine, on newsstands Friday. “There was no need to worry because Blue is great,” says the source. “She takes her job as a big sister very seriously and helps out a lot.” The superstars recently closed on an $88 million mansion closer to Blue’s school and are gearing up for a busy fall. “Blue is excited about starting kindergarten,” says the source. “She misses her friends. It will be fun for her to get back to her own life at school. Beyoncé is excited for her too but keeps saying that she can’t believe Blue is starting kindergarten. She thinks Blue is growing up way too fast!”