gistfile1.rb

class PeopleController < CrudController
  respond_to :js

  def new
    object = build_resource
    object.personable = Individual.new

    super
  end

  protected

  def update_resource(object, resource_params)
    object.localized.assign_attributes(*resource_params)
    
    if object.valid? && has_personable_and_it_changed?(object)
      personable_was(object).destroy
    end
    
    object.save
  end

  def has_personable_and_it_changed?(object)
    object.personable_type_was && object.personable_type_was != object.personable_type
  end

  def personable_was(object)
    object.personable_type.constantize.find(object.personable_id_was)
  end
end