Kensington Palace said today that George, 3, and Charlotte, 1, will be page boy and bridesmaid at the May 20 nuptials of Middleton and financier James Matthews.
They are the children of Prince William and his wife Kate, who is Pippa's sister. William, Kate and Prince Harry will all attend the high-profile wedding. It's not yet clear what role Kate, the Duchess of Cambridge, will have in the wedding party of her only sister.
Matthews proposed to Pippa Middleton last year. The couple will marry at St Mark's Church in Englefield, 72 kilometres west of London.