How Original Brady Bunch Cast Honored Florence Henderson and TV Christmases Past on HGTV Special

A Very Brady Renovation: Holiday Edition premieres tonight on HGTV — and the former Brady siblings are just as excited about it as the fans.

After making over their iconic TV home with the help of a slew of HGTV stars, the six original Brady kids are celebrating Christmas at their on-screen abode with the help of Food Network’s Pioneer Woman, Ree Drummond and Jasmine Roth, star of HGTV’s Hidden Potential. Tonight, fans can watch the group spend time decorating the newly-renovated Brady house for the holidays, as well as cooking up some classic ’70s-inspired Christmas dishes.

PEOPLE chatted with the older siblings of the bunch, Barry Williams (Greg) and Maureen McCormick (Marcia), about filming the seasonal special, and all the nostalgia the cast-mates felt along the way. Both agreed that coming back together with their TV family was the best part of the process.

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“Uniting together was the most fun,” said Williams, 65. “We’ve never truly spent Christmas together as a group, so it was really special.”

McCormick agreed: “Everybody’s been off doing different things, so we were reminiscing, but also making new memories today as adults, celebrating where we all are in our lives. I discovered new things about all these people that I love, and that was really a beautiful thing for me because that show meant so much to me and the people mean so much to me.”

The stars agree that filming the special brought back fond memories of past Brady Bunch Christmas episodes, as well.

Williams, for one, was reminded of the series’ first Christmas episode, “The Voice of Christmas,” which premiered during the show’s first season, in 1969. In the episode, mom Carol (played by Florence Henderson) loses her voice after overdoing rehearsals for the church Christmas concert.

Cindy (Susan Olsen), the youngest, tells Santa that she doesn’t want any presents for Christmas — she just wants her mom to get her voice back. In an adorable ending, Carol gets her voice back in time for the concert, and Cindy ends up with presents under the tree anyways. It was a sweet, memorable storyline that fans fell in love with.

“What’s significant about that episode is our show looked like it was going to be canceled coming into December,” Williams recalls. “So September, October, even November, were not that strong for the network, and there was a lot of dialogue about the cancellation of the series — until that episode. That episode was a turning point in our viewership. Renewals came up pretty soon after that and we were picked up and then picked up and picked up again. It never really faced that kind of danger again.”

The Christmas episode also holds a place in McCormick’s heart, as she remembers being entranced by her TV mom’s singing. Henderson, who played the Brady family matriarch, died on Thanksgiving in 2016, and McCormick was one of the first to lead Hollywood in mourning.

“I always loved hearing her sing,” an emotional McCormick tells PEOPLE. She says filming A Very Brady Renovation: Holiday Edition brought back bittersweet memories of “just all of us being together.”

Williams says he took it upon himself to say a toast during the Christmas dinner they sat down to for the special to the cast members who have died. “It was a special moment where we were able to acknowledge Robert Reed, Florence Henderson, and Ann B. Davis, who were, of course, missed,” he recalls. Robert Reed played dad Mike, and Ann B. Davis played Alice, the housekeeper.

“Barry’s toast was one of my favorite things,” McCormick said. “It was a really beautiful, sweet moment.”

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Despite the emotions, the special is also filled with plenty of fun and joyous moments, including McCormick’s favorite memory: When the six siblings walked outside and found that the yard was filled with snow.

“We knew nothing about it!” she says of the surprise. “I mean it was manufactured, but it was definitely real and cold and ice. And it made great snowballs!”

When asked if a Very Brady snowball fight ensued, McCormick only had one thing to say: “I don’t know, you’ll have to tune in!”

A Very Brady Renovation: Holiday Edition airs on on Monday, December 16, at 10 p.m. ET/PT on HGTV.