"If she's going to have another baby, why don't they just have one together even if they're not together?" says Kim

By Aurelie Corinthios
September 28, 2018 10:00 AM

The Kardashian baby boom might not be over yet.

In PEOPLE’s exclusive sneak peek at Sunday’s episode of Keeping Up with the Kardashians, Kim Kardashian West reveals that Scott Disick has been thinking about expanding his family with his ex Kourtney Kardashian. (They ended their nine-year relationship in July 2015 and share sons Mason, 8, Reign, 3, and daughter Penelope, 5.)

“So Scott just texts me that he wants to have another baby with Kourtney,” Kim, 37, tells family friend Larsa Pippen. “I think he just wants one more, and she wants one more.”

“She definitely wants more kids,” says Pippen, 44. “If they both want to have more kids, why not have them together? Their kids are gorgeous.”

“I mean, it’s like, Scott has a girlfriend, Kourtney has a boyfriend — we get it,” Kim says. “They don’t even have to have sex. It could be IVF.” (Disick, 35, has been dating 20-year-old Sofia Richie for about a year, and at the time, Kourtney, 39, was dating Younes Bendjima.)

Kim decides she needs to involve the rest of the family and whips out her phone to email them about it.

“I have to tell the rest of the family to be like, ‘Guys, should we encourage this?’ ” she says. “How cute will that be? They have to have another baby!”

“I mean, I would want all my four kids with the same person,” she continues. “When I got pregnant with North, I had no idea if Kanye [West] and I were going to end up together. I was like, ‘We can break up, but let me just at least have some sperm, so I can have another one so I could have siblings.’ ”

And at the end of the day, Kim can’t help but admit that she’s secretly holding out hope that her sister and Disick might get back together some day.

“If she’s going to have another baby, why don’t they just have one together even if they’re not together?” she says. “I think that I do hold onto this hope of Kourtney and Scott, just because I’m so used to them being together.”

RELATED VIDEO: Scott Disick Says He’s in a ‘Different Place’ in Life — ‘I Can Have Fun and Still Hold Down a Job’

But a reconciliation doesn’t seem likely, with a source telling PEOPLE this summer that Kourtney “will never get back with Scott.”

“She’s happy that he’s doing well and spending a lot of time with the kids,” said the source. “She’s happy about co-parenting with Scott, but that’s it.”

“She doesn’t mind being single and is keeping busy,” added the source. “Her kids are always her number one priority.”

Keeping Up with the Kardashians airs Sundays (9 p.m. ET) on E!