First of all, all of your sims look authentic and beautiful!
@Emily4331 for Stephanie Halloway I'm thinking of Charlize Theron but with dark hair, like here:
http://cdn-img.instyle.com/sites/default/files/styles/480xflex/public/celebrities/transformation/2005b-charlize-theron-400_0.jpg?itok=6WTuHmRU
@coco for Emiko I think about Julia Roberts, not because of the facial features, more for the colors and the general charm
https://upload.wikimedia.org/wikipedia/commons/thumb/a/a6/Julia_Roberts_2011_Shankbone_3.JPG/250px-Julia_Roberts_2011_Shankbone_3.JPG
@venusdemilosims Kaydence reminds me Selena Gomez a little, something with the hair
@GrijzePilion for Amber and Holly I would go with Emma Stone and Kristen Stewart, respectively.
@venusdemilosims for aunt Savannah I would pick Judy Greer (maybe it's just specific angle)