(Cover) - EN Showbiz - Brad Pitt and Angelina Jolie's children have been praised for their "independence", with their three-year-old twins even packing their own suitcases.

This week the Hollywood power couple were spotted boarding a train from London to Glasgow with their kids as Brad is filming scenes for World War Z in Scotland.

Sources close to the family have revealed how grown up all six kids are becoming, with twins Knox and Vivienne well accustomed to travel protocol.

One insider has told People how their ten-year-old son Maddox "is almost like a teenager now, the way he understands things".

"He's grown up very quickly," added another source.

Seven-year-old Pax "has become more independent in the past year" and the publication reports the twins "help pack their own suitcases" for family trips.

Brad and Angelina also raise six-year-old Zahara and Shiloh, five. It is thought that now all the kids are growing up they are becoming closer than ever.

"The children are always playing, jumping on each other and sharing fun moments," a source told People. "They share a special bond."

It is also believed that maturity has brought a sense of harmony to the family. The Jolie-Pitt family home is said to be a happy place at the moment.

"Now that all the children are older, things have calmed down a bit in the household," added a source.

"There's a great family dynamic right now." (C) Cover Media