Entertainment website TMZ reports Samantha's boyfriend told them the couple have had a "confrontation" with the paparazzi.
Samantha Grant, who shares a father with Meghan, is said to have been injured when a vehicle she was travelling in swerved to avoid an alleged paparazzi photographer and hit a concrete barrier.
On Tuesday, Samantha admitted she had encouraged her father to stage paparazzi photos of himself preparing for the wedding - something Thomas Sr says he's "deeply embarrassed" about now, while Thomas Jr published a nasty open letter in a U.S. magazine calling Meghan a "below C average Hollywood actress".
Just before she ended up in hospital, Samantha gave a scathing interview, where she spoke from her auto, slamming Meghan for asking her family not to speak out about her life.
Samantha Grant argued she's an American and if she wants to talk about herself and her father, Thomas Markle, she's allowed.
National Assembly May Pass Increased 2018 Budget Today
The lawmakers also increased the oil benchmark for the 2018 budget from $45 proposed by the executive to $51. The budget will have a fiscal deficit of N1, 954, 464, 993, 775 and a deficit to GDP of -1.73 per cent.
The alleged incident came after Samantha gave interviews on United Kingdom television about her half-sister's upcoming wedding to Prince Harry.
The ex-model has been criticised for making a string of waspish comments about Meghan since her engagement to Prince Harry. After the sketchy situation was exposed, Thomas pulled out of walking Meghan down the aisle at her wedding.
She said on ITV's Loose Women on Monday: "I have to say, I'm not taking it personally".
Markle's father already announced that he will not be attending the royal wedding following his controversial staged photos. "I think a person has a right to say 'enough is enough, I wasn't to be shown how I really am".
"There's no bigger media vulture with this wedding than you", he said.