Ever since Angelina Jolie adopted Maddox from Cambodia in 2002, she has been candid about her desire to adopt several siblings for him.

"I want to have a home that represents the world as I see it, which is children with all different religions from different parts of the world," Jolie told USA Today in 2003.

But that doesn't mean that Maddox was ready to share his mom, who noticed that he grew envious when she paid attention to other children.

"There was a little kid the other day, and he put his hand on me and asked me to read him a story and Maddox got very upset," Jolie told 20/20.

So how's Maddox, now 5, coping with the addition of three siblings in under two years?

"Maddox is getting over his initial jealousy little by little and he and Pax seem to be becoming good friends," says a source close to Jolie.

"Now Maddox has a playmate and they are learning to love playing together."