Pregnant Heather Rae El Moussa and Tarek Pose with Nick Cannon and Bre Tiesi's Son: 'In Training'

Heather El Moussa/instagram

Heather Rae El Moussa is getting ready to be a mom!

The pregnant Selling Sunset realtor, 35, decided to get some hands-on baby time with co-star Bre Tiesi's 6-month-old son Legendary over the weekend.

Sharing a photo and a video on Instagram Sunday, Heather wears a blue knit sweater dress as she holds the infant, whom Tiesi shares with Nick Cannon.

In the video, Heather holds Legendary in her home, as her dog Bugzy watches and the little one looks around the room.

Later, the mom-to-be shared a photo of husband Tarek El Moussa holding Legendary, writing, "Uncle Tarek in training!" adding that the baby boy was "obsessed with Tarek's beard."

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RELATED: Heather Rae El Moussa Reveals 'Super Special' Modern Nursery as Baby Son's Due Date Approaches

Heather recently teased the possibility of more babies in her future while debuting the nursery for her baby on the way to Access Hollywood.

"We still have the embryos if we decide in the future to have more," she told the outlet as husband Tarek playfully acted shocked.

Laughing, Heather shared, "He did say if we decide to have another one it just has to be back-to-back."

Tarek continued laughing himself, adding, "Yeah, back-to-back. I'm no spring chicken. I'm going to be 42."

Heather Rae El Moussa/Instagram

In addition to their baby on the way, Tarek is also dad to son Brayden, 7, and daughter Taylor, 12, whom he shares with ex-wife Christina Hall.

The couple were in the middle of in vitro fertilization treatments, and had even scheduled a date to transfer an embryo, when they were happily surprised to learn they were expecting, they told PEOPLE exclusively in July.

"It was a huge shock," said Heather at the time. "We just weren't expecting this. We had just gone through IVF. We had embryos on ice. We had a plan."

But after the disbelief wore off, Heather was elated. "I think when you least expect it and there's no stress in your life, the world just brought us what was meant to be. I'm so excited that it happened like this."