Nicole Richie  and Joel Madden  teamed up to bring their kids, Harlow and Sparrow, to a birthday party in LA yesterday. Joel's brother Benji also tagged along. Nicole showed Harlow something interesting on her iPhone, while Sparrow took a turn being a pirate with his bandanna and sword. Nicole and Harlow had their own matching fashion moment with mother-daughter hair buns. Tobey Maguire  was also on daddy duty for the mini A-list bash as he and Jennifer Meyer brought along their two little ones, Ruby and Otis, as well. Nicole kicked off her weekend with an adults-only event to kick off the Sunset Strip Music Festival alongside Joe Manganiello and Malin Akerman.