Watch: Prince Harry Preparing to Attend Duke of Edinburgh Funeral
The two princes will reportedly stand side by side as they walk behind his coffin during the funeral on Saturday.
The Duke of Edinburgh passed away at Windsor Castle aged 99 on Friday with the Queen by his side.
Harry is expected to return from the US in the next 24 hours for the funeral and will reunite with his brother who he has hardly spoken to in the last two years.
Royal sources told the Mirror how Prince Philip “urged them both to put to rest their differences, and not only remember their bond but also be mindful of their duty to the Queen and the country”.
The funeral will be the first time Harry has appeared with his family since he quit as a senior working royal last year.
Meghan, who is pregnant with her second child, will not attend the funeral, remaining in California after not getting medical clearance to travel by her doctor.
Former prime minister Sir John Major said on Sunday that shared grief over the death of their grandfather is an "ideal opportunity" to mend rifts within the royal family.
His comments came after Cardinal Vincent Nichols, the head of the Catholic Church in England and Wales, suggested a coming together for Philip's funeral could help heal any tensions.
The Duke of Sussex laid bare a rift with members of his family during an interview with Oprah Winfrey last month.
Asked during an appearance on the BBC's Andrew Marr programme, Sir John said: "The friction that we are told has arisen is a friction better ended as speedily as possible, and a shared emotion, a shared grief, at the present time because of the death of their father, their grandfather, I think is an ideal opportunity.
"I hope very much that it is possible to mend any rifts that may exist."
Harry was reportedly angered by what he perceived as his brother's "snobbish" attitude to Meghan, after William questioned whether he should rush into things with the ex-actress.
The brothers also reportedly stopped speaking for two months after the Sandringham summit over “Megxit” in January.
Watch: Prince Philip's funeral plans released
Tensions then heightened after the bombshell Oprah Winfrey interview in which the Sussexes accused the royal family of racism.
It forced William to defend his family as "very much not a racist family" during a visit to a school in the days after the programme aired.
Harry stopped short of attacking his older brother in the two-hour sit-down with Winfrey.
“The relationship is space at the moment,” Harry said. “And time heals all things, hopefully.”
He added: “I love William to bits, he’s my brother, we’ve been through hell together, we have a shared experience, but we were on different paths.”
When younger, William and Harry’s bond appeared unbreakable, and they were united in their experience of a royal childhood and the trauma of losing their mother.
They were each other’s best man on their wedding days, and Harry said when he was 21: “It’s amazing how close we’ve become.
“I mean, ever since our mother died, obviously we were close, but he is the one person on this earth who I can actually really … we can talk about anything.
“We understand each other and we give each other support.”
Broadcaster Tom Bradby, a friend of the Sussexes who interviewed them for a documentary about their Africa tour, wrote about the rift: “The fallout began at the time of the wedding in 2018.
“Really damaging things were said and done.
“The atmosphere soured hard and early, but few meaningful attempts were made by anyone to heal the wounds.”
He added: “There is no doubt Harry and Meghan feel they have been driven out.”
The Queen and Philip's children and grandchildren will gather to pay their respects to the much loved royal patriarch at the service in St George's Chapel, Windsor Castle on Saturday.
Prime Minister Boris Johnson will not be present to allow for as many family members as possible to be there amid the Covid-19 rules, Downing Street said.
The duke's long-standing close aide, his private secretary Brigadier Archie Miller Bakewell, will be one of the few, and possibly only, non-royals invited to attend the historic occasion.
Brigadier Miller Bakewell had been the duke's right hand man for 11 years, taking on the role in 2010.
The Queen's four children and their spouses - the Prince of Wales and the Duchess of Cornwall, the Princess Royal and Vice Admiral Sir Timothy Laurence, the Duke of York, and the Earl and Countess of Wessex - will be present.
The Queen and Philip also had eight grandchildren: Peter Phillips, Zara Tindall, the Duke of Cambridge, the Duke of Sussex, Princess Beatrice, Princess Eugenie, Lady Louise Windsor and Viscount Severn.
The Duchess of Cambridge, as a future queen, will also be expected to attend.
The grandchildren's other spouses - Mike Tindall, Jack Brooksbank and Edoardo Mapelli Mozzi - may attend to support their wives, but, the Queen might, given they are not senior royals, decide to include other relatives or members of the household instead.
Watch: Mourners lay flowers for Prince Philip Outside Buckingham Palace