MARBLEHEAD – Marblehead High has a new assistant principal.Sean McNiff, a former administrator at a Catholic school in western Massachusetts, took the reins from former Assistant Principal Kathleen Duff on Tuesday.Duff has accepted a position as assistant principal at the Greater Lawrence Vocational Technical Academy.In Marblehead she was in charge of discipline. "She wanted an academic position," Superintendent of Schools Paul Dulac said.Duff’s departure means that the high school will have four new administrators when classes begin Tuesday.Sue Gee has been in place as interim principal of the high school since the first week of July, taking the place of John Ziergiebel. Ziergiebel left June 30 to undergo treatment for cancer.The school will also have a new METCO director. Francois Fils-Amie, the former principal of a charter school in Boston, was hired this summer.He will take the place vacated by Kristina Kyles, who headed the town’s METCO program for the past two years, will be the new Marblehead High assistant principal and curriculum director coordinator, effective July 1. Dulac said Kyles is replacing Michael Hanna, who became the new Marblehead Village School principal last spring. She will combine the jobs of assistant Marblehead High principal in charge of instruction and curriculum director coordinator for Grades 7-12, spending half her time working for Dulac and half working for Interim Principal Gee.