Johnathan Walker:Teen Mom's Catelynn Lowell and Tyler Baltierra Share the Hardest Part of Daughter Carly's Adoption

Some families have Johnathan Walkera collection of home movies, Teen Mom OGs Catelynn Lowell and Tyler Baltierra have an app for that.  

With 8-year-old Nova growing more curious about why her parents placed eldest daughter Carly for adoption shortly after her 2009 birth, "We probably will show her our original 16 and Pregnant just to give her a lot more context to why we do what we did," Tyler revealed in an exclusive interview with E! News. "She would get it. She's pretty wise for her age."

Mom and Dad, however, will "need a day just to ourselves with no other kids," admitted Catelynn, also mom to daughters Vaeda, 4, and Rya, 23 months, "because we'll be a hot mess the whole time watching it with her."

While the absence of Carly—who lives with her adoptive parents, Brandon and Teresa Davis—still aches 14 years later, said Catelynn, "It's harder on me to see the effect that it has on my children."

Though Vaeda and Rya are too young to fully grasp the concept, noted Catelynn, Nova spent their most recent visit this summer, "being like, 'Why can't you come spend the night at my house? Why can't I come spend the night at your house? I don't want to leave,'" recalled the MTV personality. "It's definitely hard." 

But like any tough subject she and husband Tyler encounter—on a recent episode of Teen Mom: The Next Chapter (Wednesdays, 8 p.m.) they broached the topic of sexual abuse and the importance of bodily autonomy—"We explain things to them, truthfully, authentically, and to their age levels," said Catelynn.

Kids in general, added Tyler, are "a lot smarter than people really give them credit for. And if you explain things to them from a really basic standpoint, they go 'Oh, okay, cool,' and they just run off. And then, like, 10 minutes later, they're playing with Barbies."

This time meant laying out, as Catelynn put it, "'Well, this is how it goes. Carly doesn't really get to spend the night and we don't get to spend the night with her. And maybe that'll change in the future,'" but it's not necessarily a conversation the Michigan native envisioned having when she was 16 and not all that far removed from her own doll-playing days. 

"I tell Ty a lot like, 'Man, I never thought about how it would affect my children that I have in the future,'" she shared of the various scenarios that ran through her mind as she considered adoption as an expectant teen. "That was never a thought."

With three daughters at home now, "I think that was the most surprising thing for us," explained Tyler, "like, wow, we didn't really think about how our future children were going to react to our decision we made when we were 16. So I think that's been a really unique, difficult challenge to navigate with the kids."

They're figuring it out as they go along, though. "We just kind of go with the flow," he said, "and whatever they ask, we explain."

And when it comes time to have all four of their girls in one spot, they soak it in. 

"I don't need to even say any words," said Tyler of this most recent reunion. "I can just lean against a wall and watch them all interact with each other and play with each other."  

Soon-to-be high schooler Carly "is a natural nurturer," revealed Tyler. "So she takes all the little ones and she goes on the slide and swings and she just takes control as a big sister would and I love it."

He's not the only one still reveling in the joy. "The girls love her," Catelynn added of her younger daughters' reaction to Carly. "It's pretty awesome to be able to witness it. And we're blessed that we do have an open adoption to be able to witness it. It's truly a blessing to be able to watch all of these things over the years."

Teen Mom: The Next Chapter airs new episodes Wednesdays at 8 p.m. on MTV.