Hello, Thank you for your interest in our game :)
The twins and Zack's affinity story are not yet included. They will be in the next version in june.
You can check the roadmap for more info: https://trello.com/b/8W9hyU6X/rma-roadmap
Also for the hidden scene, you have to max the affinity with the tree brothers to unlock the hidden underwear (you can only see it in the morning if I remember correctly ^^)