Well, I figured out what changes I need to make in the game to trigger the new events. You need to make the bikini deal with Dylan and you need to turn down Aiden's deal and send Dylan off to boarding school. This lead to an event in 0.150 I didn't see before, with Dylan, Sam, Sophia and Amber playing in the pool... that specific event is what is needed for the new one, the four of you in the pool... so... seeing some new stuff in the old version I missed... totally forgot about the boarding school scenario. I was going through the game again anyhow to get screenshots to recreate assets so I went back and changed my choices to follow this.
Anyhow, the majority of people probably missed this as most go for the Aiden deal.
Edit: posted this before I read
clnkrazy's reply, thanks. I discovered it by checking two variables that are set in the code, working backwards I managed to piece together what needs to be done. You also need the bikini deal with Sophia.
The main variable that is set in 0.165 is "Amber_Sophia_Dylan_Sam_events", and that is set only if the "day14_Sophia_sunbathes_in_bikini_in_Dylans_presence" variable is set, and that is only set if you agree to the bikini deal with Dylan. Quite the little chain of events.
Oh, on another note...
Old Dog had mentioned that he thought that Alyssa once had star tattoos on her hand. I think I found where that memory comes from... it wasn't Alyssa, but Ellie that got the star tattoos on her hand... this scene is where Sophia first learns about Ellie's tattoos and I remembered what you said about a star tattoo on someone's hand...