The Prince of Wales and the Duke of Sussex will both separately take part in a ceremony paying tribute to their late mother at the Diana Legacy Award.
William will attend the event at the Science Museum in London on Thursday night in person, where he is expected to give a speech to mark the charity’s 25th anniversary and present awards to 20 recipients.
Harry will then join a video call with the winners, according to reports. However, his involvement will only take place after William has left the ceremony.
It comes as the royal brothers have continued to distance themselves from each other in recent months.
The pair did not meet when Harry spent time with the King at Clarence House following news of his cancer diagnosis last month.
In an interview with a US breakfast TV show, Harry said “I love my family” and that he was “grateful” to be able to spend around 45 minutes with Charles when he flew back to the UK.
Harry published his controversial memoir Spare last year, in which he accused William of pushing him into a dog bowl in a row over the Duchess of Sussex.
It was also claimed William teased Harry about his panic attacks.
Further tensions between the royal brothers can be traced back to the early period of Harry’s relationship with wife Meghan, when his then fiancee had a falling out with the Princess of Wales in the run-up to their wedding.
The Diana Award was set up to promote the princess’s belief that young people have the power to change the world for the better.
Both William and Harry presented the inaugural legacy awards at St James’ Palace in 2017.
Dr Tessy Ojo, chief executive of The Diana Award, told The Times: “It’s a privilege to have the support of both the Prince of Wales and the Duke of Sussex — particularly as we mark our 25th anniversary year.”
While a spokesman for the award told The Telegraph that Harry will be a “key part” of the celebration.
“He is scheduled to speak with the award recipients, virtually, on the evening of the awards to celebrate their accomplishments,” he said.
