Mariah Carey opens up about her kids' playdate with Blue Ivy and her friendship with Beyoncé

Mariah and Beyoncé posed backstage with their kids after at New York City's Beacon Theatre.

Mariah said she and Beyoncé are good friends.

Mariah said her children got along "great" with Beyoncé's daughter.

Mariah shares twins Monroe and Moroccan with Nick Cannon.

Beyonce and Jay Z's four-year-old daughter Blue Ivy is no stranger to backstage hangs.