It sounds as if she had to live with her grandparents because she was already in trouble. I don’t think she was really a Sunday school teacher per se. It’s more likely a title given to her just for showing up.
There was probably more going on with her than anyone wanted to admit. I doubt it was her first ‘run in’ with a little girl either.
There is something very wrong with a person who can harm a child, period.
Agreed, obviously there were many problems with that woman...