Doubling Down with the Derricos : Diez, 4, Undergoing Surgery on His Head 'Could Be Life-Altering'

When Doubling Down with the Derricos returns to TLC, the Derrico family will face one of their most trying times yet.

On Tuesday, Karen, Deon and their 14 children will invite audiences back into their home for season 2 of the reality series, which will see the couple consult doctors about their 4-year-old son Diez's skull shape.

In PEOPLE's exclusive sneak peek at the premiere, the Nevada-based parents prepare to take the little boy to his doctor's appointment, where they "hope to get answers as to what's going on with his head shape," says the stay-at-home mom.

"I dread it, it's emotional," says Karen, 41, as real estate investor Deon, 50, adds: "We know it's not going to be easy, but we have the faith that it's going to be okay."

TLC Derrico family

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As the trio gets ready to leave, Deon explains to Diez's sibling, Dior, why his brother won't be at home — marking the first time the siblings have been apart since birth.

"We are about to take your brother to the doctor," says Deon, who tells some of the other siblings to say their goodbyes, which results in a sweet group hug.

TLC Karen Derrico with son Diez

"I am so proud of our children. They are so incredibly supportive of each other," says Deon, adding that "no child can have too much love."

Karen and Deon share children Darian, 15, Derrick, 10, 9-year-old twins Dallas and Denver, 7-year-old quintuplets Deonee, Daician, Daiten, Deniko and Dariz, 4-year-old Diez and Dior, and 1 1/2-year-old triplets Dawsyn, De'Aren and Dyver.

Saying goodbye to Diez isn't easy for Dior, who begins to cry. "This is Diez and Dior's first time being separated, which in and of itself is going to be challenging," Deon says.

"Just going down this new path of what this may be with Diez's surgery is just very scary for us," says Karen, with Deon admitting, "Very scary territory. This could be life-altering."

RELATED: Doubling Down with the Derricos: Mom Karen Spends '$3,500 a Month' to Feed 14 Children

TLC Dior and Diez Derrico

TLC Karen and Deon Derrico with son Diez

Last month, PEOPLE debuted the supertease for the upcoming season.

"His head is very elongated — that may be a thing called sagittal craniosynostosis," a doctor told Karen and Deon in the clip. "It can cause coordination issues, developmental delays. We're going to put you [in touch] with a team of neurosurgeons in UCLA."

"The surgery is dangerous, I can't do this, I can't," Karen later told the cameras, walking away.

Doubling Down with the Derricos premieres Tuesday at 8 p.m. ET on TLC.