For chloe, you have to play the board game where you take off your clothes. Then chloe wilp get horny and arroused and it follows through to the next tike you can invite her to your room(only when she goes and sees your sister).
and then you'll have enough arousal to try and have sex with her. (Obviously you'll still have to do all options you can to get her to the max arousal)
Took me a while to figure it out too. The other one, I have no idea still.