I think you need to "practice" how you will respond to her when she comes out with a new snide remark (and I'm sure she will). The best way to handle her is to look at her as if she were the same age as D3, smile and slowly shake your head, then turn and walk away. No remarks, explanation....nothing. Let her wonder what you were thinking. She's baiting.
It is not about what you feel should work in your M. It is about doing the work that gets the right results. Do what works!
