For those having problems with the 3 wives in the Residential Area, you
MUST have enslaved the Hospital so that you can speak with the Doctor about the patient examination and then complete the patient examination
BEFORE you go to the Residential Area. After that when you return to the Residential Area you should have a scene where you fuck the 3 wives without the Principals family around, after that you go back to the Hospital Front Desk and you should now have an option to impregnate the 3 wives (and possible some others, depending on progress).
Speaking with the Doctor and completing the patient examination is the part that actually unlocks pregnancy, so if you haven't done that part yet ...... get it done!