Scout, Rumer and Tallulah Willis.Photo: Rumer Willis/Instagram

“Me and my 3 best buddies,” Scout added in her own captionalongside the same photo.
“That’s happy ❤️,” wrote stepmomEmma Heming Willis, who married Rumer, Scout and Tallulah’s fatherBruce Willisin 2009. The couple has two children together:Evelyn Penn, 8, andMabel Ray, 10.
Never miss a story — sign up forPEOPLE’s free daily newsletterto stay up-to-date on the best of what PEOPLE has to offer, from juicy celebrity news to compelling human interest stories.
Celebrating the joyous news, Scout did not hold back how excited she is to become a proud aunt.
“Activating hot, kooky, unhinged Aunt Scout era 🌱,” she wrote on a post in December, with a black-and-white shot of Rumer and boyfriendThomas sweetly smooching her belly.
“Thank you@rumerwillisand@derekrichardthomasfor co-creating my new best friend,” Scout added.
In another black-and-white photo, Rumer showeda silhouette of her figure, with a beautiful white winter wonderland displayed through the floor-to-ceiling windows behind her.
The Willis/Moore family is known for being a tight-knit clan, especially as they support one another through Bruce’s recently disclosedfrontotemporal-dementia diagnosis.
The family first announced last Marchthat he was “stepping away” from his decades-spanning acting careerfollowing his diagnosis withaphasia, a language disorder that is “impacting his cognitive abilities.”
“This is a really challenging time for our family and we are so appreciative of your continued love, compassion and support,” they said at the time.
The family added, “We are moving through this as a strong family unit, and wanted to bring his fans in because we know how much he means to you, as you do to him. As Bruce always says, ‘Live it up’ and together we plan to do just that.”
source: people.com