So, it was natural for Angelina Jolie and Gwen Stefani to get their children together when they coincided on this side of the Atlantic.
The Hollywood supermum dropped in on Gwen's London home with four of her six children.
Gwen divides her time between California and the Primrose Hill district of the capital because her husband Gavin Rossdale is British.
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Their five-year-old Kingston (left) has his birthday the day before Angelina's little girl Shiloh (centre) in May.
And, the actress' twins, Vivienne (bottom right) and Knox (top right), are the same age as Kingston's brother Zuma, three. Making up the group was Zahara, six, who trotted out behind Shiloh.
The youngsters looked like they had a ball together, with several of them sporting face paint on leaving.
Glam globetrotter Angelina has become a dab hand at keeping her lively bunch entertained on the go.
She's been pictured popping into an arts and crafts shop in Richmond and on trips to the London Aquarium and the theatre.
In Britain, while dad Brad films a zombie thriller, the Jolie-Pitt clan has attracted plenty of media attention.
Such was the commotion caused in the street by their presence that neighbour Jools Oliver, wife of TV chef Jamie, was seen looking out of a window to see what all the fuss was about.
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