Okay guys regarding Iris, I managed to trigger the phone quest because I didn’t even pursue any of Lily’s taboo and the game threats each encounter as meeting her for the first time BUT the phone encounter is the only way to get her to spawn into the game as an NPC that can be interacted with. If she is only met during the mom event, she just shows up on your phone and that’s it.
As for anyone who was wondering (like me), the only NTR stuff I found for Jennifer is with high stats, she might mention she doesn’t get any attention from from other men. You are given the choices of telling her to “go commando”, make a move on her, or let it go. If you choose the commando option, she texts you afterwards that she hooked up with coworker and sends you a picture of her ass covered in cum. Outside of the added NTR night events; there is not other explicit events that I have seen for both Lily and Jennifer. I even made sure the mom has maxed out slutty stats and even kept her dosed up with my fully upgraded pregnancy/slut serums.
With the fact that other NPCs can get pregnant from their own partners (at least I think so), I’m surprised two of biggest main characters in the game doesn’t have their own non-incest partners (NTR or otherwise). So one possible scenario is if you don’t actively pursue them; both Lily and Jennifer can get their own partners that they date. Lily can start the game already dating a classmate in college that you can get her to cheat on or breakup with, and Jennifer can end up dating a coworker right after the start of the game that lead to by helping her get the work promotion (or you can prevent by failing to help her or hiring her to your company) that you can get her to cheat on with you as well. The developers can still reuse the nighttime NTR events where you can watch them and depending on their taboo and sluttiness scores; they can yell at your for watching or let you join like in the current Jennifer NTR event.