She continued: “For my sister to go into a church knowing what she has done to our father, ignoring him through every holiday, the wedding, two heart attacks the birth and the christening, is disrespectful.
The news comes after Meghan made headlines this week for guest editing Vogue’s iconic September issue.
The Duchess is the first person to guest edit the magazine's September issue in 103 years, and it isn't a role she took lightly.
As part of her collaboration with editor-in-chief Edward Enninful, Meghan picked out 15 trailblazing women to feature on the cover.
“She wants women’s voices to be heard but she’s got a sister in a wheelchair that she has coldly ignored and tried to silence,” added Samantha, who is in a wheelchair due to MS.
“And I hope that Archie is of strong character and will not be silent and will stand against her overexertion of control.”
WATCH: Meghan attends the Polo with baby Archie