I think you might be a little wrong with your assessment, because this final preview is more indicative of what was written some time ago. I wrote that Josy, Maya, Jill, Isabella and Sage probably won't be at the DIK Panty Party. The reasons are obvious. Josy and Maya don't want to walk around half-naked in front of their brothers.
Jill won't present herself half-naked in front of lots of strangers, considering she has stage fright. Isabella, as a teacher, will definitely not appear at a DIK Panty Party. Sage has personal problems with her parents' divorce.
So what does the preview show us?
The five LIs are having their own party. The MC will be at the DIK Panty Party first and then have to make a decision, just like in EP4. If the MC stays at the DIK Party, he can talk to Josy and Maya or he can go to Jade. The same thing awaits us in EP11. If the MC stays at the DIK Panty Party, he will mess things up with the LIs, but he can fool around with the many "Other Girls". Or we can decide to drive to Isabella in Rusty's car and be with all the LIs, but that will exclude many "Other Girls".