I don't know how you define main, but probably the girls at the house + Lilith. Rest is not completely decided yet, I'll probably do a new poll on the popularity of the girls after next two episodes to get a better feel on things.
I say this as someone who likes the cop LI a LOT. Less is more with Love Interests. Better to have deeper, richer content that makes a bigger deal with plot and character development, than a massive shallow pool that gives everyone a single taste and nothing more.
Make one girl afraid to do anal, and slowly work through that together. Or maybe the mom just can't get on board with the idea of a threesome with her daughter.... until you
convince her. Putting the harem together shouldn't be simple or easy like collecting fucking baseball cards*, it should be the heart of the story, or at least part of it.
*TS fell into the trap of just throwing girls at us without any chase, and having them all just accept being in a harem. Which cheapened the achievement IMO. I say this with great love and respect for your first entry Dev.