MARBLEHEAD – Mainstream public school administrators are readying themselves for a possible increase in enrollment in Grade 4 in response to what appears to be a sharp split on the board of the Marblehead Community Charter Public School.Five members of the MCCPS Board of Trustees resigned after a 6-5 vote to retain Thomas Commeret as head of school and some of the dissenters have indicated that they are considering their children’s return to the Marblehead Village School or the Marblehead Veterans Middle School.The 12-year-old school houses 225 children in Grades 4-8, or 25 students per year and a significant drop there could affect next year’s school budget.Interim Superintendent of Schools Philip Devaux told the School Committee Thursday night he is considering adding an additional fourth grade teacher to maintain class size at the Marblehead Village School.Devaux also said he is sending a letter to all third grade parents, asking them to tell the School Department where they will be sending their children next fall.”If they don’t let us know in a timely way their children may have a classroom but no teacher in place. We’ll be hiring that teacher in July or August and that’s not the optimum time to hire a teacher,” Devaux said.”Now that they’ve (the Department of Education and the MCCPS) made certain decisions we see concrete evidence that there’s going to be a change,” he added.The MCCPS board voted 6-5 March 14 to retain Thomas Commeret as head of school after some heated meetings, prompting the resignation of Commeret’s five opponents. He and trustees on both sides of the question met with representatives of the state Department of Education March 23 to discuss what a DOE spokesman called the school’s “concerns.”The DOE told Commeret and the trustees to revise their bylaws to bring them in line with state guidelines or face revocation of their charter, and to provide the DOE with monthly reports on finances and enrollment.Three members of the pro-Commeret majority were teachers at the school, who said they were refusing compensation for the time they spent on the board in order to comply with a legal opinion from the State Ethics Commission.The DOE has ruled that teachers and employees of the school should not vote on Commeret’s contract, regardless whether they are being paid, and required the three members to provide proof that they are not receiving compensation. The remaining board members must appoint two more members who are not employees.