April 18, 2016 04:30 PM

Eric Christian Olsen and Sarah Wright Olsen‘s baby on the way already has a best friend.

The NCIS: Los Angeles actor’s costar Daniela Ruah and his older brother David Olsen are expecting their second child this fall, the mom-to-be announced Monday on Instagram.

Sharing a photo of herself and husband Olsen exercising outdoors with their 2-year-old son River Isaac, Ruah, 32, writes, “There are four people in this photo, can you spot them all?”

The actress, whose baby bump is on full display in a fitted tank as she lifts weights, also shared a quote from Carl Sagan.

“For small creatures such as we, the vastness is bearable only through love,” she wrote.

David Livingston/Getty

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Ruah and Olsen met on NCIS: Los Angeles, where she plays Special Agent Kensi Blye. Olsen, 40, a former Navy SEAL, has acted as his younger brother’s stunt double on the CBS drama.

Eric and Sarah’s new addition, a baby girl who will join their 2½-year-old Wyatt Oliver, will arrive this summer, they announced in March with a sweet snapshot of their son gripping his mama’s growing belly.

— Anya Leon

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