One place you really can't show up without calling first is Kensington Palace.
On Saturday, Samantha made a decision to show up at the Palace uninvited to try and talk to Meghan, according to E!News.
Needless to say, it wouldn't be surprising if Samantha did exactly the same.
According to the Mirror, Samantha Markle had given palace officials an "ultimatum" in which she said she would show up to confront her sister if they did not arrange a meeting.More news: 'That was something': Trump left speechless after Kanye visits White House
She then handed a letter to be delivered to the Duchess. She was accompanied by her partner, who pushed her in a wheelchair.
But, on Sunday, Samantha teased her Twitter followers, writing, "Everybody would love to know what's in that letter".
Samantha, 53, was pictured outside the gates of the palace in London after travelling from the United States.
Samantha said that if she got the chance to speak to Meghan, she would tell her it's "water under the bridge" and recognize that their issues spiraled "out of control".
"Dad only spoke out because he was being ignored and disregarded", she wrote.
However, as eyewitnesses told, she could pass a note to sister (if it came to the recipient, is unknown), the contents of which, of course, curious to many.
Grant said she was hurt that some in the family weren't invited to the wedding (their father, Thomas Markle was, though he couldn't make it because of health concerns).