Crypto-Monster Parent

A year and a half ago, I was an English teacher of Sara, Mrs.M's daughter.
Mrs.M is a fashionable& beautiful woman, who is almost the same as my age. Also, she "looks" friendly.
When I met her for the first time, I thought, "I want to be her friend!"
...But the "fantasy" was broken soon.

Two weeks later I started to teach Sara, we had parent observation classes.
After the lesson, Mrs.M called my manager, and said, "Keiko is not experienced. Please change the teacher for Sara."

I had many excuses. Sara turned a certain age when she was easily distracted. I had an "obvious" monster parent after her lesson, so I was busy with making strategies for her... But I couldn't argue against Mrs.M! I was dismissed from Sara's teacher.
After that, I heard Mrs. M often called "our headquarters" not our school branch, when she had complains about my successor. Yes, she was..."crypto"-monster parent!!

10 months later, Mrs. M wanted Sara's younger daughter, Nana, to start taking English lessons. Nana became 15 month-old at that time.
Who was in charge of the baby's class? Me! Mrs.M requested me to give her trial lesson.

Then, a "miracle" happened. Nana was a difficult baby, who always started crying when she met new people... But she kind of "fell in love with" me.
I don't know why, but she always stopped crying when she saw me and smiled.

8 month later I started to teach Nana... Now she tries to repeat everything what I say. Mrs. M is very satisfied with that! Mrs.M told me, "Nana LOVES you very much! When she behaves bad, I always say, "I'm going to tell Keiko sensei about your bad behavior!" Then she says, "Please don't!" and stop doing it!"

...Is that a God's trick?? Anyway, from next semester, I keep teaching Nana, AND I restart teaching Sara, again! It means I will be in charge of all kids of the crypto-monster parent! Can I keep making her satisfied??? I don't know...