Kody Brown and his wife Robyn are weighing their options when it comes to potentially adding another sister wife into their family.

In PEOPLE’s exclusive first look at the season 20 premiere of Sister Wives, Kody, 56, tells his wife, “I think you and I share something very special, but if it’s not duplicatable, it could put us at risk.”

Calling their relationship “wonderful,” Kody explains that adding another sister wife could change the dynamic between them.

“Why would we put that at risk?” he says of their relationship. “For anything other than…”

“A guarantee,” Robyn, 46, interrupts, which she calls “not possible.”

During the conversation, Kody admits that “there’s something I want, maybe more than you do.” Robyn then appears puzzled and asks, “What? What do you mean?”

“I don’t want to talk about that subject,” Kody says, and Robyn responds, “Oh, you’re talking about sex.”

When considering another sister wife, Kody then reveals his “primary motivation” is about physical attraction.

“I’m afraid, at this state in my life, [it] would be just how good looking she is,” he confesses. “I’m not kidding.” His wife is unimpressed, saying, “And that would be the very worst reason.”

Kody insists that he would “want to be able to connect” with a new partner, but Robyn says, “You don’t understand how you’re coming across.”

“I know, I know. I’m a guy and I don’t freaking care,” he replies.

However, Robyn teases in a confessional that Kody is “just kind of being a bit of a pig right now.”

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The conversation comes after fans saw Kody inform Robyn that another woman expressed interest in joining the polygamous family in the Sister Wives season 20 trailer, which was released in August.

“I got another one of those emails from some woman asking sort of like to get to know us for the purpose of joining the family,” Kody told Robyn, which didn’t appear to please her.

Kody’s former wife Christine Brown — who was the first to end her marriage to the Brown patriarch before Meri and Janelle Brown — weighed in on whether there was “a chance” the pair would bring in a new sister wife during an appearance of The Sarah Fraser Show earlier this month.

“I do not even know how to wrap my mind around what I have seen that they are even entertaining,” Christine admitted.

She went on to question the pair’s true intentions for considering an addition to the family, explaining, “Are they? Is it just for camera? I do not know. I just don’t know. But, I hope not, because what they have is a soulmate situation. They really do.”

She added that she felt “so disingenuous” and “so unfair” for the couple to bring in another wife.

“Kody himself, he talked about how much he loved monogamy,” she noted. “So why do that? Why ruin something so good?”

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Sister Wives season 20 premieres Sunday, Sept. 28, at 10 p.m. ET on TLC.