Her half-brother, Thomas Markle Jr., confirms he hasn't been invited — nor has Meghan's half-sister, Samantha Grant, for that matter.
Now Thomas — who early on defended Meghan against critical comments made by Samantha — is speaking out to accuse Meghan of mistreating her family and trying to reinvent herself as a new Princess Diana.
"Meg likes to portray herself as a humanitarian, a people's person and a charitable person, but she is none of those things to her family," Thomas told Britain's Daily Mirror newspaper.
"She is giving the greatest performance of her life. She is acting phony. Once she got into Hollywood, she turned into a different person. She's clearly forgotten her roots and her family," he added in the April 19 report. "Maybe the normal American family she has is embarrassing to her because we're not producers and executive producers."
According to Thomas, 51, his sister changed after finding fame as an actress on the legal drama "Suits." And her behavior since has "torn my family apart."
Thomas, who lives in Oregon and shares a father with Meghan, told the Daily Mirror that from 2009 to 2011, he saw her often, spending every other weekend with her as they helped take care of their grandmother, Doris, who had dementia.
Meghan, he said, "was great with her. Meg would read to her all time. We were so close back then, but when our grandmother died, she moved to Toronto to start filming 'Suits' and I didn't see her. I haven't seen her since late 2011."
Despite his deeply critical remarks, he insisted, "I'm not bitter, just baffled. It's hurtful given how close we once were."
"I'm confused and a little distraught because here is a person knowing the position she's in and knowing the scrutiny she's under and yet she has forgotten her flesh and blood," he added.
Thomas insists that he started speaking to the media only to defend Meghan against hurtful comments made by Samantha. "That's how I got involved in this, coming to Meghan's defense. But trying to put a lid on Samantha and get her to be quiet backfired and started a rift of insults," he explained to the Daily Mirror.
"None of us has heard a word from Meg and what with all that has been said no longer do I speak to Samantha or my two sons. I had hoped Meg might have appreciated the support I gave, but it's meant nothing to her, it would seem," he added.
According to Thomas, he's reached out to his half-sister via the palace three times in hopes of connecting and clearing the air, but without the desired result. His most recent email to one of Meghan and Harry's communications officers, he said, "has been completely ignored. They did not even acknowledge its receipt. That whole thing is hurtful."
Thomas made no apologies for his about-face and criticisms of his sister as her wedding date approaches. In fact, even after sharing how loving and caring she was with their grandmother, he's said she'll never be worthy of any positive comparisons to Harry's late mother, Diana.
"There's a whole different side of her that has started to surface and it's ugly to see," Thomas told the Daily Mirror. "I've read that Meg wants to be like Diana. Diana was worshipped by everyone in the world. She was loved for the right reasons. That's what Meg wants, but I don't think that's going to happen. She's not genuine like Diana."
Tom Jr. concedes that a January 2017 incident in which he was arrested on weapons-related charges following a domestic dispute with his girlfriend — though the charges were dropped — could have upset his sister and be one reason he's fallen out of favor. However, he argues, "No family is perfect. All families have their disputes and troubles."
He did not address how Meghan might feel about him repeatedly speaking out about her to media outlets over the last year.
It's been reported that about 600 guests have been invited to attend Meghan and Harry's wedding ceremony on May 19 as well as a lunchtime reception to follow that will be hosted by Queen Elizabeth II at St. George's Hall. Just 200 guests are being invited to a separate evening reception at nearby Frogmore House that's being hosted by the groom's father, Prince Charles.
Tom Jr. told the Mirror that he thinks Charles should get involved — along with the queen herself — to urge Meghan to reconnect with her estranged family members.
"Isn't this where Charles or the queen step in and say, 'This is the way things are done. And your family need to be involved.'"
Tom isn't the only relative who's upset with Meghan and the absence of a royal wedding invite. On April 11, Samantha gave her sister — from whom she's been estranged for years — a piece of her mind in an epic rant on her private Twitter account, MailOnline reported.
"At issue is not a matter of closeness as more than 1000 complete strangers are invited. Family is family I have an uncle I have only seen once but I would never say he is not family because we are not close. Humanitarians move forward with love and kindness especially to Family," Samantha wrote in part.
Tom Jr. and Samantha both lived in the same household as their newborn half-sister when they were teens. Their dad, Thomas Markle Sr., married Meghan's mom, Doria Ragland, in 1979. The former Hollywood lighting director, 72, and the social worker and yoga instructor, 61, split when Meghan was 6.