Harry and William both agreed to keep communication open to reunite on July 1 for the event, and it will be the first time they see each other following the funeral of their grandfather Prince Philip.
The two reunited just before their grandfather's funeral, as they met at a gathering at Windsor Castle before the procession behind Prince Philip's coffin started.
Harry and William were also spotted walking and talking to each other after the service, coming face-to-face for the first time in years.
Now, the pair will reunite once more, this time coming together to pay tribute to their mother.
In a rare joint statement by Harry and William, the brothers revealed that a new statue of their late mother is to be unveiled in the Sunken Garden of Kensington Palace next month.
"Our mother touched so many lives," William and Harry's statement read.
"We hope the statue will help all those who visit Kensington Palace to reflect on her life and her legacy."
WATCH BELOW: Prince Harry and Prince William play with Princess Diana
According to The Sun, both brothers have been involved in the process of creating the sculpture, and have been committed to working together and letting go of their issues in respect of their mother.
However, a source revealed to the publication that it’s unlikely the two will be seen together on camera.
“William and Harry are as far apart as it’s possible to be—emotionally and physically. Their relationship is at rock bottom. William’s raging with Harry after the Oprah interview," the insider said.
“He is so angry with him that it’s totally unthinkable at the moment for them to be happily reunited and stood together at the unveiling of the Princess Diana statue. It’ll take a lot of work to patch things up so they can put on united front,” said the source.