Four decades since the first book of “The Baby-Sitters Club” series came out, creator and author Ann M. Martin is looking back.“When I set out to write the first book in The Baby-Sitters Club, ‘Kristy’s Great Idea,’ I wanted to create a series about girls who were strong, entrepreneurial, independent thinkers, and problem-solvers — and friends who were kind, compassionate, and supportive of one another despite their many differences.”Now, nearly four decades later, I receive letters fr
