The Duke and Duchess of Sussex’s “heartbreak” following the Duke of Edinburgh’s death will be documented in the new epilogue of a book about the couple.

Finding Freedom has been updated since its publication last summer with a new chapter that publisher HarperCollins said will also recount “Meghan’s emotional healing journey from losing a child to the birth of their daughter”.

Co-authors Omid Scobie and Carolyn Durand’s book chronicles the duke and duchess’s romance and brief period as members of the monarchy before they broke away to forge a new life for themselves and son Archie in America.

HarperCollins said the epilogue in the paperback edition will share: “Behind the scenes of Harry and Meghan’s ground breaking interview with Oprah, details behind the couple’s move to California (and) the various philanthropic and business endeavours the Sussexes have been involved with since their move and what’s to come with Archewell Productions.”

It will also feature: “The continuous challenges the couple face regarding privacy and the British press (and) the heartbreak the couple felt over Prince Philip’s death.”

The updated book, which goes on sale on August 31 – the date Diana, Princess of Wales was killed in a car crash in 1997 – is said to have been written with the participation of those closest to the Sussexes.

The reasons behind Meghan and Harry’s decision to step down as working royals and move to California last year were revealed for the first time, seven months after the book’s publication, in the couple’s interview with Oprah Winfrey.

The couple left the royal family in crisis with a series of shocking revelations that painted the monarchy as a racist and uncaring institution.

Meghan and Harry laid bare their brief life as a working royal couple, alleging a member of the family – not the Queen or Philip – made a racist comment about their son, and how the duchess had suicidal thoughts but her approaches to the monarchy for help were turned down.

Winfrey was left open-mouthed when the duchess – the first mixed-race member of the modern British monarchy – said a fellow royal was worried about how dark their son Archie’s skin tone might be.

Harry is to write his own tell-all memoir and has promised to give an “accurate and wholly truthful” account of his life.

Home life during the break-up of the Prince and Princess of Wales’s marriage, the period of Diana’s death and its aftermath, Harry’s relationship with Camilla and past girlfriends are likely to form part of the book which will be eagerly anticipated by readers.