version_parent_observer.rb

class VersionParentObserver < ActiveRecord::Observer
  observe MyModel, MyOtherModel

  [:create, :update, :destroy].each do |action|
    define_method("after_#{action}") do |record|
      increment_version_for_observed(record, action)
    end
  end

  private

  def increment_version_for_observed(record, action)
    unless record.skip_observation_on.include?(action)
      record.observed_parents_to_version.each do |parent|
        parent.increment_version!(record.observers_column) unless parent.new_record?
      end
    end
  end
end