The siblings played several arcade games and appeared to be in good spirits as seen in their respective social media accounts.
Chrissy Teigen also Snapchatted from the party, sharing videos of herself and husband John Legend having a fun date night. The Lip Sync Battle star also posted a selfie video of herself with the birthday girl.
Though recent episodes of Keeping Up with the Kardashians showed tensions between Rob and his sisters following the surprise news of his engagement, dynamics have since changed post-filming.
An insider previously told WHO, that the family has now come around to Rob's romance, acknowledging that Chyna has had a positive impact on the dad-to-be's life.
"They feel like Chyna saved him," the insider said. "The [Kardashian sisters] have gotten over their issues with Chyna now. They've welcomed her in."