Details of the claims - including more information about Meghan's fractured relationship with her father in the days before her wedding to Prince Harry - have been published in court documents as part of Meghan's legal action against the Mail on Sunday.
The arrangements Meghan made for Thomas Markle's accommodation and flights, and her attempts to shield him from the intense media interest, were set out in a legal reply to the paper’s owners, Associated Newspapers.
The Duchess is suing the Mail on Sunday for publishing the contents of a private letter she sent to her father a few weeks after the royal wedding.
The Mail on Sunday has claimed - as part of its defence for publishing the letter - that it had already been spoken about in an article in People magazine in the US.
Five of Meghan's friends spoke anonymously to People to support her after what the Duchess calls the "false and damaging" articles about her in UK tabloids.
In her latest court submissions, Meghan insists she did not authorise her friends to speak, did not know they were planning to do it, and wasn't aware of the article until it was published.
One of her friends, referred to in the court papers as Friend A, had told the magazine about Meghan's letter to her father.
The Duchess maintains her privacy was invaded when the Mail published the letter and she is also seeking damages for breach of copyright.
Her legal team says she was "vulnerable" at the time and suffering from "tremendous emotional distress and damage to her mental health".
The legal papers say that Meghan's friends were "concerned for her welfare, specifically as she was pregnant, unprotected by the Institution and prohibited from defending herself."
It's the first time she has claimed in public that she thought the Monarchy had not sufficiently supported her and did not sufficiently push back against the articles about Meghan during her pregnancy.
The submission says that both the Duchess' friends who saw her in the UK - and those who hadn't - were "equally concerned for her mental health and wanted to help".
And Meghan's legal team says her friends had a "shared frustration" that the Royal Family insisted they all "remain silent". That is how she explains her friends decision to speak to People magazine.
She also describes in detail how she went to great lengths to keep her letter to Thomas Markle private - explaining how she had sent it via her "trusted business manager" in the US and sent a copy to her US lawyer "for safe keeping [...] on the understanding that he would not read its contents."
Meghan has not spoken to her father since the wedding in May 2018 and Thomas Markle has neither met his son-in-law, Prince Harry, nor his grandson, Archie.
The Mail on Sunday maintains the publication of the letter was in the public interest and strongly rejects Meghan's claims that it breached her privacy.