Last week Harry and Meghan relocated from California, six years after the Megxit crisis, with their children Prince Archie and Princess Lilibet.
Just weeks ago during a brief summer visit, Harry took his children, who are now enrolled in British schools, to see Diana's resting place for the first time.
The princess is buried on a tiny island in the Round Oval Lake on the Althorp estate in Northamptonshire - the Spencers ancestral home where Diana's brother Earl Spencer lives.
Next year marks the 30th anniversary of the princess's sudden death in a Paris car crash.
Diana - the ex-wife of King Charles – was killed on August 31, 1997 when Princes Harry and William were just 12 and 15.
The anniversary comes just three weeks before Charles Spencer prepares to release his deeply personal memoir to counter "untruths" about her life.
His new book Swan Song: Diana, My Sister is due out on September 22 and will contain "many revelations that will draw considerable attention", according to its publisher.
The earl famously delivered a passionate eulogy at her funeral, pledging the princess' "blood family" would protect William and Harry "so that their souls are not simply immersed by duty and tradition, but can sing openly as you planned".
"With the 30th anniversary of Diana's tragic death on the skyline, I've been inundated yet again with requests for interviews about my sister," Spencer said.
"This has convinced me to write down my own thoughts and memories, once and for all, rather than having the discomfort of again reading the opinions of others, many of which are based on untruths that have become accepted over time."
Devoted fans of the princess usually gather each year at the gates of her former London home Kensington Palace to leave flowers and other tributes.
In the Palace's Sunken Garden stands the bronze statue of Diana commissioned by William and Harry, and unveiled by the estranged brothers together in 2021.
The pair put on a united front despite their rift to reveal the sculpture on what would have been their mother's 60th birthday.
Their strained relationship deteriorated further during Megxit, after Harry's accusations against William and other family members in his Oprah interview, Netflix documentary and memoir Spare.
William and the Princess of Wales have yet to comment on Harry and Meghan's return.
The brothers will be expected to mark this year's anniversary separately, with a reunion on the 30th anniversary looking unlikely.
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