The only 2 girls in the basement are sweet slut and bitch, sweet slut is on the right side of the basement after you see her while renting a room. If you didn't see her there, be sure to talk to the guy at the counter. Bitch is outside the club, you open the door to the right of the club, go inside and enter the club via the passage. After you talk to her outside the club, follow her into the secret passage building and talk to her again. She should be in the basement on the left side after this.
She should be standing right outside it.
EDIT: Since people are having trouble with some girls i will create a shortened and edited version of the guide, covering no gameplay but just the girl instructions only.
Edit 2: Attached is the shortened guide which gets rid of all the fluff and just gets down to brass tax which is girls only. Do note it still follows the guide in the way i got them. I did however update it with a section on the succubus but i didn't bother to go back myself to get her so i just put information that i think is relevant and from what i read here and elsewhere.
Please update the walkthrough for these girls:
Succubus
Map says "From the longest dock, between the sandy paths, take 8 paces east, and one south. That is where the treasure is buried." Once you dig the spot you get $50 and a gold amulet. That money should help with buying the Wine for the ritual (2nd wine after buying the one for Bougie). After buying the wine and leaving, the bartender will stop us and give us a Red-Light Reserve for free. The Red-Light Reserve is all we need for the ritual. So the ritual needs: Spellbook (from Takano's Office), bloody rope, Red-Light Reserve, Gold Amulet from the beach and finally chant Merunyaa.
Sweet slut
Only needs 1 beer in my playthrough. I bought the beer after seeing her leave room 7. I went to the basement and talked to her. Her terms were 1 beer for 1 fuck. I gave her the beer and she was down. She will ask for 1 more beer to fuck again.
Cop
After getting her the donuts and sitting next to her on the park bench, she'll be too stuffed to move. This persists even after impregnating every other girl except for Natasha. She won't head down the elevator to check the lab. I think you have to first speak to Natasha > Other work > Get Food. She'll ask you to get fast food from Duck Donald's. After that speak to Natasha again to request Other Work > Breeding Test Subject. She'll talk about luring the cop down to her lab to get data on getting her pregnant. That's when you'll need to talk to her about the fake $100 bill and then give her the Pumpkin Spice Latte. She'll sort of follow you to the abandoned warehouse with the elevator (south of the club)
Everything else you have seems to be right