Credit: Courtesy of Scout Masterson

Baby on deck! Scout Masterson and Bill Horn, known as the Guncles to Tori Spelling's brood of four (Liam, 6, Stella, 5, Hattie, 2, and Finn, 16 months), are ready to expand their own family!

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The couple, who wed this past July after more than a decade together, signed up to adopt a sibling for daughter Simone, 3, over the holidays, they reveal exclusively to Us Weekly. "We thought long and hard about it," Masterson, 39, tells Us of the decision. "We put it on hold for a year, and then we just thought it felt right."

The pair is hopeful that the adoption process for their second child will be quick. "[The process] took a year and a half with Simone," Masterson explains. "What they said to us is because we have a child and they can see that she's three and a half, they see pictures of her on Facebook and they see that she's a happy child  that we'll get picked faster, knock on wood."

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Even though Masterson and Horn have no preference as to the baby's gender, the soon-to-be big sis Simone is certain that the bundle of joy will be a girl. In fact, the three-and-a-half year old already cast her vote on a name -- Harper after her BFF Harper Smith, daughter of Tiffani Thiessen. Too cute!