More doubts about whether Meghan Markle's father will attend his daughter's wedding Prince Harry on Saturday, it is reported, he should be operated on heart
Thomas Markle had told the US website TMZ, he would not go in a row on paparazzi photographs; then he would do it; then that he could not because of a planned heart surgery.
Kensington Palace declined to comment.
Ms. Markle's alienated half-sister said he had faced "incredible stress."
Samantha Markle, speaking on Australia's Sunrise Morning TV program from Orlando, Florida, said she was not sure if Mr Markle would travel to Windsor.
"He sent me a message that he is undergoing heart surgery," she said.
"We all hope he's going through this now."
Markle became involved in controversy over the weekend after he reportedly staged paparazzi photos of himself in advance of the wedding.
The images showed Mr. Markle ̵
TMZ later reported that Mr Markle wanted and wanted to participate – although he could not for health reasons.
And in a third report, the website said that the health problems and the planned operation would deter him
On Tuesday evening, BBC Royal correspondent Nicholas Witchell said that Markle wanted her dad to be there, but her main concern would be for be his welfare.
Kensington Palace said the events were "a deeply personal moment for Mrs. Markle."
"She and Prince Harry once again ask for understanding and respect for Mr. Markle in this difficult situation," the palace said in a statement on Monday.
Mr Markle had to meet Prince Harry for the first time this week, as did the Queen and the Duke of Edinburgh, before walking down the corridor of his daughter in St. George's Chapel at Windsor Castle.  Samantha, who has not spoken to her famous sibling in three years – and will not be attending the wedding – told Good Morning Britain that the photos were made "with good intentions" and not for money.
Images had been her idea to present a positive image.
By Jonny Dymond, BBC Royal Correspondent
People around Meghan Markle say she has no thought about her father They walk down the aisle.
The pressure has been utterly merciless, and she and Prince Harry have been worried about Thomas Markle's state of mind for some time.
He seems to have been caught up by the amazing pressure that fell on him. Whether by design or coincidence, he fell into this photo agency fraud.
We have another example of this unfortunate back of kingship – that is the extraordinary pressure of media attention, a part of it caused by the fact that the royal family demands the attention of the press to maintain their relevance.
Read more about Jonny here.
The ex-suits actor's father lives in Mexico and is a former lighting director who worked on programs such as the 1980s television series Married with Children and General Hospital, for which he and his team won two Emmy Awards  He and Markle's mother, Doria Ragland, divorced when Mrs. Markle was six years old.
Markle, who has two children – including Samantha – from her first marriage, filed for bankruptcy
Ms. Markle said earlier: "It's safe to say that I've always been a daddy's girl – he taught me how to fish to appreciate Busby Berkeley movies, write thank-you notes and spend my weekends in Little Tokyo eats chicken teriyaki with vegetable tempura. "
The wedding will take place on May 19 at 12:00 in the St. George's Chapel in Windsor.
Five days before the wedding, Kensington Palace has announced that Ms. Markle will be spending her last night before marrying in a luxury hotel in Buckingham. Hotel with her mother Doria
Prince Harry will be with his brother, the Duke of Cambridge, 15 miles away in the Coworth Park of the Dorchester Collection in Ascot.