Sasha
Sasha is there and super excited to be celebrating his dad's birthday. In true teenage guy fashion he'll probably eat his weight in pizza and it won't take much coaxing from Shelby to get him to play in the ball bit - I mean you're never to old to play in a ball bit, right? He's probably a mildly aware of everyone's curiosity about Shelby, but he also likely knew the minute he invited her that they would be so Sasha isn't surprised by this.