It should not be possible to add a subarea that overlaps with an existing subarea.
When adding or editing a subarea map we should validate the polygon against the existing polygons in the system and disallow saving if it overlaps with one that already exists.
It should not be possible to add a subarea that overlaps with an existing subarea. When adding or editing a subarea map we should validate the polygon against the existing polygons in the system and disallow saving if it overlaps with one that already exists.