Is it possible to sleep with Alison, Cherry and Emma in whatever constellation or is that a difficult decision?
You can.
At the first go out, you choose stay with Cherry, make convo then go look for Alison and choose I like you. Then when you go back, make eye contact with Cherry, pick her up then shag. (Alison fucks Jeremy here)
A few days later Alison asks you out if you said we should meet again when you meet them all at the fortress. Very straight forward here, choose to compliment options then bring her to your home and shag.
When you go to club, leave Perry at the house. While dancing either focus on Emma or dance with charisma. Then grind, talk, more grind, kiss. With that way, you can bring Emma to your house. (again snake fucks Alison)
When you meet with Cherry, Alison duo at the Fortress. Flirt with Cherry, ask her to come to your place. She'll refuse at first, then when she learns Alison is fucking Jeremy. You'll have a chance to convince her. Choose that. Second Cherry shag.
When Jeremy asks threesome, accept.
When Emma comes to your place before meeting with friends, fuck her again.
If you follow these, Cherry and Emma will be fwb and Alison as a side piece. If you don't mix other LIs as serious relationship then you can see all the Emma and Cherry scenes and can have threesome scene with Alison. Also, a few other scenes with Alison. (like after Gillian scene)
P.S. go heavy on charisma to collect enough points.