I have gone to Utopia, in fact I have Heather, Megan and Emily enslaved already and working at my club. An odd thing was when Emily joined, Mom and Nicole were in pillories in the Private Room, even though I haven't been able to enslave them. I had the problem before then, though.
After taking a hiatus for a couple of months and then coming back to the game, I finally solved this. To reiterate the problem I had, I was not able to enslave either Jenny (Mom) or Nicole (Sis) in spite of having VERY high Stats for them, while I WAS able to enslave Megan, Emily, and others with lower Stats and SEEING Mom & Sis at the Private Room at Utopia.
I solved the conundrum by visiting Utopia a second time. The game treated it as my FIRST time, giving me a new tour and instructions. Then when I picked "Make (Mom) a slave", I was able to take her (and later Sis) to Utopia. That also enabled Mrs Simpson. Apparently, you have to make Mom your FIRST slave for events to precede "properly".
So far, I have 7 main slaves- Jenny/Mom, Nicole/Sis, Megan, Emily, Heather, Mrs Simpson (PLEASE give her a first name!) and Sister Maria. Principal Michelle has agreed to be my slave, but not gone to Utopia (she wants to go with her family at the same time) and the 4 other teachers apparently come along when you enslave Michelle. The walkthrough also mentions the lifeguard at the school pool. But what about Aunt Julia and the twins or Dr. Anne at the hospital? Can I enslave THEM in the current update (v 1.95)?
The new update looks great. Points for MORE Lesbian Incest and Pregnancy. I also applaud the dev for Bravery with the playground girls. (Personally, I'm hoping for some Doggie sex in the future, and I mean sex WITH Dogs, not the girls ACTING like dogs!)
Good luck!