Chappaqua Superintendent Lyn McKay said she was the one who signed off on a controversial legal defense in a lawsuit against the school district pertaining to sex-abuse allegations against a former teacher. McKay said that the decision to do so was because of legal advice from two law firms: the district's regular counsel of four decades, Shaw, Perelson, May & Lambert, and Henderson & Brennan, a White Plains firm assigned to the district by its liability insurance company.