Fans first learned of Khloe's desire to have another child when the KUWTK trailer debuted last month, but the full conversation with Tristan is all-new.
"Kim, every time I post a video of True, she DMs me and she's like, 'She can't play by herself her whole life,'" Khloe tells Tristan of her sister, Kim Kardashian West.
"In my head, when I was going to have kids, I never, ever imagined having an only child. Especially being on quarantine with her, I felt bad. She had no friends. She had nobody. They were isolated even from each other (True's cousins) for so long," she continues. "I don't know. True's getting older and I just feel like it's now time to have another kid."
Tristan seems more than on board with the plan, excitedly nodding his head and smiling as he says, "Yep. Mmmhmm. [That's what] I like to hear."
Khloe, who froze her eggs months before the conversation, begins discussing the logistics.
"We have to line it up with your schedule, so I can make embryos with my frozen eggs," she tells her beau, who sweetly responds, "I'm all for it."
"I think I'm ready to do the whole pregnancy thing again," Khloe says. "This process might take time. I have no idea. So I think [we] start the process, at least be prepared."
Both Khloe and Tristan say they think "it's gonna work" to have another kid, before the NBA star shares that it's not just one more baby he wants.
"I've always wanted four kids, so I have Prince and True," he says of his 4-year-old son from a previous relationship and his daughter with Khloe. "Two down, two more to go."
"OK. Well, we'll just have to see what happens," Khloe responds.
Earlier this week, a source told ET that "having more kids has definitely been a conversation" for the couple.
"Khloe has been very vocal and adamant about wanting a big family," the source said. "She of course sees herself marrying Tristan one day, but he has a lot to prove in order for their relationship to elevate to that level."
The source said that Khloe and Tristan "are back to being committed, are still in love and giving their relationship another chance and hoping that it will succeed this time around." The source's comments came after Tristan's 2019 cheating scandal, which, the source said, Khloe "forgives" Tristan for.
The source noted that, while the couple is separated as Tristan plays for the Boston Celtics, they stay in frequent communication.
"Tristan has been paying extra attention to Khloe and True and has been calling, FaceTiming, texting and sending photos all the time to check in when they are not physically together," the source added. "He hasn’t been going out late at night with the boys or other girls."
The final season of Keeping Up With the Kardashians premieres Thursday, March 18 at 8:00pm ET/PT on E!.