included.rb

module IncludableOne
  def self.included(base)
    base.register_on_save :includable_one_saved
  end
  
  def includable_one_saved
    puts "Saved One"
  end
end

module IncludableTwo
  def self.included(base)
    base.register_on_save :includable_two_saved
  end
  def includable_two_saved
    puts "Saved Two"
  end
end

class MyBaseClass
  include ActiveModel::Model
  def initialize
    @callbacks = []
  end

  def register_on_save(callback)
    @callbacks << callback
  end

  def save
    @callbacks.each do |callback|
      send(callbak)
    end
  end
end

class MyDerivedClassOne < MyBaseClass
  include IncludableOne
  include IncludableTwo
end

class MyDerivedClassTwo < MyBaseClass
  include IncludableOne
end

derived1 = MyDerivedClassOne.new()
derived1.save
derived2 = MyDerivedClassTwo.new()
derived2.save