The identity of Harry's best man, for instance. It's only a few months now until Prince Harry and Meghan Markle tie the not — but from the sounds of it there are still a few key wedding details they haven't yet planned out.
Prince William, Duchess Kate and Prince Harry together
Prince William, Duchess Kate and Prince Harry together
Britain's Kate, Duchess of Cambridge, and Prince Harry applaud Prince William after his speech during a training event to promote the charity Heads Together, at the Queen Elizabeth II Park in London, Britain, February 5, 2017. REUTERS/Alastair Grant/Pool
Britain's Prince William, Kate Duchess of Cambridge and Prince Harry (L) stand ready to give an award during a visit to The Mix in London, December 19, 2016. REUTERS/Alastair Grant/Pool
HAYES, UNITED KINGDOM - APRIL 20: (EMBARGOED FOR PUBLICATION IN UK NEWSPAPERS UNTIL 48 HOURS AFTER CREATE DATE AND TIME) Prince William, Duke of Cambridge, Catherine, Duchess of Cambridge and Prince Harry attend the official opening of The Global Academy in support of Heads Together on April 20, 2017 in Hayes, England. The Global Academy is a state school founded and operated by Global, The Media & Entertainment Group, educating students for careers in broadcasting and the digital media industry. (Photo by Max Mumby/Indigo/Getty Images)
Kate Duchess of Cambridge, Prince William, and Prince Harry (R) greet guests attending the Patron's Lunch, an event to mark Britain's Queen Elizabeth's 90th birthday, in London, June 12, 2016. REUTERS/Peter Nicholls
LONDON, ENGLAND - APRIL 05: Prince William, Duke of Cambridge, Catherine, Duchess of Cambridge and Prince Harry attend the Service of Hope at Westminster Abbey on April 5,2017 in London, United Kingdom. The multi-faith Service of Hope was held for the four people killed when Khalid Masood committed an act of terror in Westminster on Wednesday March 22. Survivors, bereaved families and members of the emergency services joined The Duke and Duchess of Cambridge, Prince Harry, the Home Secretary, Amber Rudd and London Mayor, Sadiq Khan, in the congregation. (Photo by Dan Kitwood/Getty Images)
LONDON, UNITED KINGDOM - FEBRUARY 05: (EMBARGOED FOR PUBLICATION IN UK NEWSPAPERS UNTIL 48 HOURS AFTER CREATE DATE AND TIME) Prince Harry, Prince William, Duke of Cambridge and Catherine, Duchess of Cambridge join a Team Heads Together London Marathon Training Day at the Queen Elizabeth Olympic Park on February 5, 2017 in London, England. (Photo by Max Mumby/Indigo/Getty Images)
The Duke and Duchess of Cambridge and Prince Harry leaving the Institute of Contemporary Art in London where they outlined the next phase of their mental health Heads Together campaign.
Catherine Duchess of Cambridge, Prince William, Duke of Cambridge and Prince Harry visit the Visitors Centre during the Somme centenary commemorations at the Thiepval memorial in France on July 01, 2016
The Duke and Duchess of Cambridge and Prince Harry at the Patron's Lunch in The Mall, central London in honour of the Queen's 90th birthday, in an open topped Range Rover.
Prince Harry, the Duke and Duchess of Cambridge leave St Paul's Cathedral in London following a national service of thanksgiving to celebrate the 90th birthday of Queen Elizabeth II.
Prince William, Duke of Cambridge, Prince Harry and Catherine, Duchess of Cambridge, wearing a skirt by Banana Republic and a blouse by GOAT Fashion, arrive to attend the launch of the
Heads Together campaign at Olympic Park in London on May 16, 2016
The Duke of Cambridge (left), The Duchess of Cambridge (centre) and Prince Harry (right) attend the World Premiere of Spectre, held at the Royal Albert Hall in London.
The Duke and Duchess of Cambridge and Prince Harry arriving for the annual Commonwealth Day service at Westminster Abbey, London, on Commonwealth Day.
Catherine, Duchess of Cambridge, Prince William, Duke of Cambridge and Prince Harry visit The Tower Of London's Ceramic Poppy installation 'Blood Swept Lands and Seas of Red' by artist Paul Cummins, commemorating the 100th anniversary of the outbreak of First World War.
The Duke and Duchess of Cambridge and Prince Harry watch riders at the finish line of Stage 1 of the Tour de France in Harrogate.
Prince Harry, the Duchess of Cambridge and the Duke of Cambridge watch a fly-past by the RAF on the balcony at Buckingham Palace following the Trooping the Colour parade, London.
Prince Harry, the Duchess and Duke of Cambridge with their wands on the set used to depict Diagon Alley in the Harry Potter Films during their visit to Warner Bros studios in Leavesden, Herts where the popular movies were produced.
The Duke and Duchess of Cambridge watch with Prince Harry during the Team Eventing Jumping Final on day four of the London Olympic Games at Greenwich Park, London.
The Duke and Duchess of Cambridge and Prince Harry chat with children during a visit to Bacon's College in Greenwich, London, where they attended the launch of a new sports project that aims to train the next generation of sports coaches.
Prince William (left), Catherine, Duchess of Cambridge and Prince Harry stand on the balcony at Buckingham Palace during the Diamond Jubilee celebrations in central London.
The Duke and Duchess of Cambridge talks to Prince Harry before a reception in the Waterloo Chamber, before her Sovereign Monarchs Jubilee lunch at Windsor Castle.
Prince William and his bride Kate leave Westminster Abbey, London, after their wedding, followed by Prince Harry (rear, left) and Pippa Middleton (rear, right).