Katharine McPhee Models Swimsuit From Stepdaughter Sara Foster's Line One Month After Giving Birth

Katharine McPhee isn't hiding how impressed she is by her family member's latest business venture.

The 37-year-old Scorpion alum took to her Instagram Story on Thursday, April 1 to share a selfie as she modeled a one-piece swimsuit from stepdaughter Sara Foster's new swim line. This comes just a month after Katharine and husband David Foster welcomed their first child, newborn son Rennie, in February.

"Best one piece I've ever tried," Katharine gushed about the look. "Usually it's cut too low and the torso isn't long enough - straps are adjustable. So comfortable you nail it @SaraFoster."

Sara, who recently partnered with Summersalt to launch her family-focused Cotton Candy Skies collection, reposted the pic on her own Story and added, "Had a baby a month ago. Wtf!"

Katharine also shared a shot of herself holding up a tiny pair of swim shorts from the collection with the caption, "This is too cute!"

Sara, 40, reposted that one as well and wrote, "Baby boy trunks for Rennie. The cutest."

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This is not the first time Sara has stepped into the apparel space, as she and sister Erin Foster, 38, launched clothing brand Favorite Daughter late last year.

Music producer David, 71, is also dad to Allison Jones Foster, Amy Skylark Foster and Jordan Foster.

Clearly, Katharine is in a summertime state of mind. On March 30, the former American Idol runner-up had proudly shared a bikini shot to her Instagram Story.

"Loving my curves because my baby gave them to me," she captioned that one at the time.