Kensington Palace aides reportedly helped Meghan Markle write an apparently 'private' letter to her estranged father Thomas Markle, according to the court documents.
The Duchess of Sussex is suing the British tabloid over an article which reproduced parts of the handwritten letter sent to Thomas Markle, 76, in August 2018.
Prince Harry's wife has claimed the the tabloid breached data protection and copyright laws by revealing extracts from the 'private and confidential' letter.
But lawyers for ANL have claimed in documents filed at the High Court in London that the letter was not the 'own intellectual creation' of the 39-year-old royal.
They argue that the Kensington Palace communications team 'contributed to the writing' of an electronic draft, which the letter was later 'copied' from.
The documents, according to 'Mail Online', state: 'It is for the claimant (Meghan) to prove she was the only person who contributed to the writing of the electronic draft.
'Without prejudice to the generality of the foregoing, the defendant infers that Jason Knauf and/or others in the Kensington Palace communications team contributed to the writing of the electronic draft.
'Precisely which parts were the result of such contribution is uniquely known to the Claimant, Jason Knauf and others in the team.'
It comes after it emerged the duchess's privacy action against the tabloid will not be heard until autumn next year after being postponed last month for a 'confidential reason'.
Justice Warby agreed on October 29 to adjourn the trial – which was due to start on January 11 next year – until the autumn following an earlier private hearing.