When Meghan Markle and Prince Harry's relationship came to the public's attention, the world fell in love with the sweet and humble actress.

She's been seen at several goodwill events, advocating for the less fortunate, and has also written a foreword for a charity cookbook to benefit the victims of the devastating Grenfell Tower fire.

But while's it already been four months since Meghan has become an official member of the British royal family, it doesn't look like her relatives will be keeping quiet anytime soon.

Who Is Samantha Markle?

Without question, the most outspoken member of Meghan's family is her parental half-sister Samantha Markle, 53, who is prone to dragging the former Suits star's name through the mud.

Samantha, who is also known by the name Samantha Grant, is 17 years Meghan's senior; she and her brother are Meghan's half-siblings. To date, she's been the most vocal member of the Markle family, speaking out about her half-sister in the press.

Here's what else we know about her:

• Samantha and Meghan have the same father.
• Samantha was rumoured to be appearing on Celebrity Big Brother in the UK.
• Samantha accused Meghan of not supporting their father.

• Samantha has spoken up about accounts that paint Meghan's family life as less than stable or supportive.
• Samantha insists she did not smear Meghan in the press.
• Samantha is writing a book. (but it might not be a juicy tell-all)
• Samantha and Meghan last spoke in 2015.
• Samantha did not go to Meghan and Harry's wedding or Meghan's first wedding.
• Samantha Markle claims she brought up Meghan for 12 years when they were growing up.

What has Samantha Markle done now?

Samantha has recently taken aim at Harry, 35, when she wished him a backhanded "Happy Birthday" on September 15.

"Happy Birthday Harry! As you 'Mack down' on your birthday cake, think about the birthday wishes you never extended to your FATHER-IN-LAW," she tweeted.

Alongside the passive aggressive tweet she posted a gif of a hamster with a reddish fur, similar to the Duke of Sussex's own hair. The rodent is seen "mack down" on a piece of cake with a poker chip nearby.

When Meghan celebrated her 37th birth on August 4, her estranged sister wished her a happy birthday before scrutinizing her for her treatment of their father.

"Happy Birthday Meg!" she tweeted. "It would be so lovely and appropriate of you to send DAD a BELATED birthday card for his July 18th."

"Act like a humanitarian act like a woman! If our father dies I'm holding you responsible, Meg! @KensingstonRoyal," she continued.

Earlier this month Samantha took another shot at Meghan by giving her the cruel nickname of DuchAss - a play on words to her title of Duchess of Sussex.

"I am not candy coating anything anymore! The DUCHASS should be humane to our father who has given her everything,.. and this media crap can stop! He was  the one who was always there for her. Fake waves and smiles can stop. The duchASS can bow to the daddy," she wrote.

Meghan's relationship with her father Thomas Markle began to deteriorate when he staged photos with the paparazzi, which showed the patriarch being measured for a suit for his daughter's wedding.

The 74-year-old eventually revealed he would no longer attend Meghan and Harry's nuptials, citing his recent heart attack as the excuse. However, royal insiders have speculated the father of three had become embarrassed from the negative press he had been receiving.  

Things haven't improved between Thomas and his daughter when he publicly claimed "she'd be nothing without me."

"What riles me is Meghan's sense of superiority," he complained to the Daily Mail in July. "She'd be nothing without me. I made her the duchess she is today. Everything that Meghan is I made her

He didn't stay quiet and most likely tampered his already poor relations with Meghan's in-laws as he called them a "cult" this past August.

"They are either like Scientologists or the Stepford family," said in an interview with The Sun. "If they hear anybody say anything they just lock the doors."

"They need to speak up! They are cult-like "” like Scientology "” because they are secretive. They close the door, pull the shades down and put their fingers in their ears so they don't have to hear."

[H/T: Us Weekly, The Sun]

Do you think Samantha and Thomas have gone too far? Let us know in the comments!