Onchan commissioners have written to all MHKs asking them to reject proposals to split the community.
The idea going before Tynwald later this month would see Howstrake moved from Onchan to a new "East" constituency of Garff and Onchan parish.
The suggestion is in the Boundary Commission Report which suggests twelve, two seat constituencies with roughly equal numbers of voters in each.
But commissioners in Onchan say the latest proposals still "fracture the community".
The board was previously unhappy Birch Hill was going to be moved to the new constituency.
They believe the latest proposals will still remove what they call a "developed community structure" to create areas they say will not be representative of the communities they serve.
The board says the link between local and national politics will be lost for people in the new constituency.
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