<?xml version="1.0" encoding="utf-8" ?>
<hibernate-mapping xmlns="urn:nhibernate-mapping-2.2"
                   assembly="Domain"
                   namespace="Domain">
  <class name="Parent" table="Parent" >

    <id name="Id">
      <generator class="guid.comb" />
    </id>

    <version name="LastModified"
                    unsaved-value="0"
                    column="LastModified"
                     />
   
    <property name="Name" type="String" length="250" />

    <bag name="ParentChildren" lazy="false" table="Parent_Children" cascade="all-delete-orphan" inverse="true">
      <key column="ParentId" on-delete="cascade" />
      <one-to-many class="ParentChildren" />
    </bag>
   
  </class>

  <class name="ParentChildren" table="Parent_Children">

    <id name="Id">
      <generator class="guid.comb" />
    </id>

    <version name="LastModified"
                    unsaved-value="0"
                    column="LastModified"
                     />
   
       <many-to-one
      name="Parent"
      class="Parent"
      column="ParentId"
      lazy="false"
      not-null="true"
       />
   
  </class>
</hibernate-mapping>

        [Test]
        public void Test()
        {
            Guid id;
            int lastModified;
            // add a child into 1st session then detach
            using(ISession session = Store.Local.Get<ISessionFactory>("SessionFactory").OpenSession())
            {
                Console.Out.WriteLine("Selecting...");
                Parent parent =  (Parent) session.Get(typeof (Parent), new Guid("4bef7acb-bdae-4dd0-ba1e-9c7500f29d47"));
               
                id = parent.Id;
                lastModified = parent.LastModified + 1; // ensure the detached version used later is equal to the persisted version
               
                Console.Out.WriteLine("Adding Child...");
                Child child = (from c in session.Linq<Child>() select c).First();
                parent.AddChild(child, 0m);

                session.Flush();
                session.Dispose(); // not needed i know
            }

            // attach a parent, then save with no Children
            using (ISession session = Store.Local.Get<ISessionFactory>("SessionFactory").OpenSession())
            {
                Parent parent = new Parent("Test");             
               
                parent.Id = id;
                parent.LastModified = lastModified;
               
                session.Update(parent);
                session.Flush();
            }
        }