Answer:Mr. Sheffield needed someone to manage the kids, not necessarily babysit them. Brighton was a Bart Simpson type, Maggie was shy and awkward and Gracie had personality issues.
Answer:It's a bit of a stretch plot wise, but she is supposed to be more than just a "nanny." She oversees the kid's activities, manages the household, and generally keeps the family running smoothly in the absence of a mother. She is more like a family member rather than an employee.
Answer: Mr. Sheffield needed someone to manage the kids, not necessarily babysit them. Brighton was a Bart Simpson type, Maggie was shy and awkward and Gracie had personality issues.