Diana's brother Charles Spencer will host the shindig.
Tessy Ojo, chief executive of the Diana Award, hasn't confirmed the news, but said: "We’re delighted that we still have the support of the Duke of Cambridge and the Duke of Sussex. Right now, we’re the only charity that has both of them involved. It really is a privilege."
"To us, it doesn’t matter where in the world they are," she continued. "They are jointly committed to the awards. The dukes will be heavily involved as it will be a whole week of events, so they are eager to take part."
The siblings reunited in April after Prince Philip died and then again when they unveiled Princess Diana's statue in July.
While they looked happy at the latter event, an expert doesn't believe that the two are moving forward just yet.
"I am still not convinced that there is a looming reconciliation," Kinsey Schofield claimed. "I don't suspect that it is a priority for Prince William to patch things up with Prince Harry as they are at severely different stages in their lives. It appears that Prince William is busy trying to support his family through death and scandal while Prince Harry is concentrating on projects that are financially beneficial."
She added, "Prince William is prioritizing legacy while Prince Harry is focused on survival. I believe both brothers need time. Deaths, births, remembrance ceremonies, we look at all of these as a fresh start or an opportunity for renewed relationships but the reality is, all of these significant moments are happening within a Sussex PR tornado that is wreaking havoc on the royal family. It is hard to look past some of the recent revelations while you're still picking up the pieces."