The Duchesses of Gloucester and Kent and the Countess of Wessex were similarly honoured by Her Majesty.
Of her male relations the GCVO is held by the Dukes of Gloucester and Kent and Prince Michael of Kent. The Duke of Edinburgh was admitted to the Order only recently. The Duke of Sussex is KCVO, a notch down in the Order.
The Duke of Cambridge, a Knight of the Garter, has yet to be admitted.
Neither the Prince of Wales or the late Diana, Princess of Wales were members of the Victorian Order.
When the Duke of Cambridge eventually ascends the throne he will most likely follow recent royal tradition and install Catherine as a Lady Companion of the Order of the Garter.