A delusional stepmom who has zero understanding of what her role is supposed to be.
The crazy overstepping stepmom wanted to prove she was just as good as that the kids' mother, so at the first opportunity she signed up for mommy and me classes, bought a shirt that said Worlds Best Mom and told the kids, "Just call me mom, I'm like practically the same thing."
Sue: Look that mom over there breastfeeding, isn't that sweet.
Jane: Hey, I know her, she's that child's crazy overstepping stepmom!
Dad: You know honey, you are so great I think you ought to just replace my ex-wife altogether.
New Wife: Great, I'll sign up for the PTA tomorrow, can I take little Janie to get her ears pierced?
Dad: You're perfect, there's no other crazy overstepping stepmom like you.