I remember when Kristen returned in 2012 and went to EJ's office. He opened the door and blandly said "Oh, mother??" (which means Susan must've worn her Kristen disguise around EJ enough for him to think it was her) and Kristen snapped "I'm not old enough to be your mother."
Ummmm, YES, yes, you are, since you literally pretended to be pregnant with EJ and passed him off as your baby, John Jr. until the truth came out.