Michael Bublé and Kids Help Wife Luisana in Baby Bump Art Tradition Ahead of Baby No. 4

Luisana Lopitano/Instagram

Michael Bublé's family is sharing a sweet tradition in the weeks before they become a family of six.

On Monday, Bublé's wife, Luisana Lopilato, 34, shared photos from an art project with her whole family. The group worked together to make a cast of her pregnant belly, which she revealed is an ongoing tradition in a caption written in both English and Spanish.

"As in all pregnancies, just two weeks before the birth, we transform the belly into art to have our little memory at home. We are waiting for you baby girl! 💗," she wrote, thanking her doula for assisting with the project.

The photos show the couple's three kids, Vida, 3, Elias, 6, and Noah, 8, helping to hold down the plaster and keep the strips in place.

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Luisana Lopitano/Instagram

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Speaking to PEOPLE in May, the singer, 46, said they are savoring every moment before baby No. 4's arrival.

"We're really trying to be present with the pregnancy because, most likely, it's the last time," the singer said. "I want it to be really special for [Luisana], and I know it goes really fast. Since it's probably the last one, I just want to make sure that we're really enjoying every second of it."

Just as excited as Bublé and Lopilato about the new baby are their kids, who have already started weighing in on names.

"If it's a little boy, my boys want to name him after themselves, which doesn't work," he laughed. "If it's a girl, my daughter has decided that Snowy for Snow White is what the girl would be named. I think we need help."

Michael Bublé/Youtube

The couple first revealed that they are expecting another baby in his music video for "I'll Never Not Love You," which premiered in February.

In the video, Bublé and Lopilato recreate some of the most romantic scenes in cinematic history, including iconic sequences from movies like The Notebook, Love Actually and Titanic. At the end, Bublé is brought back to reality where he is met by his wife — who reveals her baby bump — and their three kids.

"I think it's already crazy. I think we're already living crazy land, so it's just going to get better," he told PEOPLE at the Billboard Music Awards in Las Vegas. "We're so blessed to have healthy kids and a lot of love on our house. There's a lot of noise. I would have it no other way. We're so lucky."