In another clip from the new trailer, Thomas Jr. was seen in the diary room where he said he would write a letter to Harry and Meghan. "Dear Meghan and Harry, the first thing I want to say to both of you is …" he began before the clip cut off.
In a previous teaser for the reality show, Thomas Jr. said that he warned Prince Harry that Meghan is "going to ruin your life. She’s very shallow." Thomas Jr. was seen arriving at the Big Brother house and announced he was "Meghan Markle's brother, I'm the biggest brother of them all."
"I’m not bitter, just baffled. It’s hurtful given how close we once were," he said in the trailer when asked about not being invited to the royal couple's wedding. "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."
Meghan and Engelson were reportedly first linked in 2004. They tied the knot in 2011 before divorcing 18 months later. The estranged couple cited "irreconcilable differences" as the reason for the split.
Meghan and Harry are said to have met on a blind date in 2016. The pair tied the knot in 2018.
The Duchess of Sussex has previously opened up about her strained relationship with her family. In March, she told Oprah Winfrey that she didn't "feel comfortable talking about people that I don't really know" after it emerged that her sister Samantha was writing a tell-all memoir.
"I think it would be very hard to tell all when you don't know me. I mean, this is a very different situation than my dad [Thomas Markle], right? When you talk about betrayal, betrayal comes from someone that you have a relationship with," Meghan told Winfrey.
Meghan cut off her father after he reportedly staged paparazzi photos of himself preparing for her wedding.
"I think Meghan should have handled this differently. I think Meghan should have handled this from the beginning and I think it got ignored and swept under the carpet for so long, it's a shame where it's ended up, especially between her and my father," Thomas Jr. previously told the Daily Mail about the rift. "She's capable of doing anything, she's just got to want to do it. If she wants to make amends, by all means, she can do that."