In deciding whether a position should be accreted into an existing bargaining unit, the Division determines whether: 1) the disputed position was included in the original certification or recognition; 2) the parties' subsequent conduct, including their collective bargaining agreements, disclose whether the parties treated the position as included in the unit; 3) the position shares a community of interest with other positions in the unit. Town of Somerset, 25 MLC 98, 100; Hanover School Committee, 24 MLC 83, 87 (1998).