class Person
  include Mongoid::Document
  has_and_belongs_to_many :awards, :inverse_of => nil
  embeds_many :somethings
end

class Award
  include Mongoid::Document
  has_many :persons, :inverse_of => :awards, :foreign_key => :award_ids
end

class Something
  include Mongoid::Document
  embedded_in :person
  
  field :name
  
  after_create :update_activity
  
  def update_activity
    person.awards.first.update_attributes(:updated_at => Time.now.utc)
  end
end

    p = Person.create!
    a = Award.new
    p.awards << a
    
    s = Something.new :name => "first"
    p.somethings << s
    
    assert_equal 1, p.reload.somethings.count # this fails