The walkthrough says you can have a threesome with sydney but the choice never appeared, please help
The threesome is unlocked for replay at the end of Ch16. If you kept a save around the beginning of Ch15 and Naomi is BI and you've had sex with Sydney, the option will come up. Also, the threesome in the endings requires one of them to be main love, you selecting Sydney when asked about threesomes later in the game.