In a new clip from the upcoming season of the Little People, Big World, the couple prepares to bring son Josiah Luke home from the hospital.
"I'm definitely nervous," Tori admits in the exclusive clip shared with PEOPLE. "It definitely didn't go well when we brought Lilah home from the hospital."
There's then a flashback to that first moment when Jackson met his baby sister, where he didn't want to go near her or Tori when visiting them in the hospital.
"I'm expecting the worst but hoping for the best," she adds, to which Zach agrees.
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When the couple walk in with baby Josiah in his car seat, Jackson runs directly for his mom, who instructs him to be "gentle."
Things went much better for Jackson the second time around, with the kindergartener becoming excited when he discovers he has a new baby brother, whose name — Josiah Luke Roloff — he carefully repeats.
Lilah walks over to the car seat, focusing on the baby. She briefly walks away before walking back over and continuing to look at him pensively.
"Oh yeah, oh yeah," the 5-year-old chants, jumping around and pumping his fists.
"We thought he was gonna lash out or freak out, everyone was gonna start crying ... but it ended up being fantastic," Zach says of the moment in a confessional.
Fans can also see the moment when grandma Amy Roloff gets to hold Josiah for the first time, which leads to some early sweet big sister moments from Lilah.
"His little eyes are open. They opened a little bit," she marvels.
Lilah then brings over a blanket for her grandma to use on her baby brother as Amy continues to hold him.
"Best big sister ever," Tori says.
Little People, Big World airs on Tuesday at 9:00 ET/ 8:00 CT on TLC.