<class name="Post" table="T04_POSTS">
...
   <set
   name="postalBags"
   cascade="all-delete-orphan"
   inverse="true">
   <key column="POST_ID"/>
   <one-to-many class="PostalBag"/>
   </set>
...
</class>

<class name="PostalBag" table="T04_POSTAL_BAGS">
...
   <many-to-one name="post" column="POST_ID" not-null="true"/>
...
</class>

   Post post = new Post();
   post.setId(new Long(1));
   post.setName("Post-11112");         
   PostalBag pb2 = new PostalBag("bag-44");
   post.addPostalBag(pb2);
   session.saveOrUpdate(post);

public class Post{
    private Set postalBags;
...
   public void addPostalBag(PostalBag bag){
      if(postalBags == null)
         postalBags = new HashSet();
      postalBags.add(bag);
      bag.setPost(this);
   }
...
}

public class PostalBag {
     private Post post;
  ...
}

   Post post = new Post();
   post.setName("Post-111");
   
   post.addPostalBag(new PostalBag("bag-1"));
   post.addPostalBag(new PostalBag("bag-2"));
   session.saveOrUpdate(post);

Before update:

T04_PoSTS                       T04_POSTALBAGS
=========                       ===============
ID   Name                       ID   POST_ID   NAME
---------------                 -------------------
1    Post-111                   1     1        bag-2
                                2     1        bag-1


After update:

T04_PoSTS                       T04_POSTALBAGS
=========                       ===============
ID   Name                       ID   POST_ID   NAME
---------------                 -------------------
1    Post-11112                 1     1        bag-2
                                2     1        bag-1
                                3     1        bag-44

<class name="Post14" table="T14_POSTS">
    <set name="postalBags"  cascade="all"
   inverse="false" table="T14_POSTAL_BAG">
   <key column="POST_ID" />
   <composite-element class="PostalBag14">
      ...
       <property name="name"/>
     </composite-element>         
        </set>
...
</class>

public class Parent {
  private Long parentId;
  private List children = new ArrayList();
  private String name;

   /**add property getters & setters **/

  public void addChild(Child c){
    this.children.add(c);
  }
  public void addChildren(List childrenList){
    this.children.addAll(childrenList);
  }
 

}

mapping parent.hbm.xml
<hibernate-mapping >
  <class name="Parent" table="PARENT">
    <id name="parentId" column="P_ID">
      <generator class="native"/>
    </id>
    <property name="name" column="P_NM" not-null="true"  />

    <list name="children"  lazy="false" cascade="all, delete-orphan" >
        <key column="P_ID" not-null="true" />
        <list-index column="SORTING_INDX" />
        <one-to-many class="Child"/>
    </list>       
  </class>
</hibernate-mapping>

public class Child {
  private Parent parent;
  private Long childId;
  private Date myDate;
/** getters and setters **/
}

mapping child.hbm.xml
<hibernate-mapping>
  <class name="Child" table="CHILD">
    <id name="childId" column="C_ID">
      <generator class="native"/>
    </id>
    <property name="myDate" column="C_DT" />
    <many-to-one name="parent" class="Parent" column="P_ID" not-null="true" insert="false" update="false" />

  </class>
</hibernate-mapping>

My DAO save/update method:

public Parent saveParent(Parent p) {
  if(p.getParentId()==null)
   getHibernateTemplate().save(p);
  else
   getHibernateTemplate().merge(p);
  return p;
}

Test it
public ResultUI findParent(SearchCriteria criteria){
     //create my detachedCriteria from my business criteria object   
     //find the parent using detachedcriteria
     //convert result to UI object and return
}

/** called from web Layer
      You can add child / remove child or update a child in the ui List
      Remember - existing child should have childId and new child will
      have a null id - for hibernate to do appropriate query
**/
public ResultUI saveParent(ParentUI pUI) {
     //convert UI object to my parent
     Parent p = new Parent();
     p.setParentId(pUI.getParentId());
     p.setName(pUI.getName());
   
    List children = new ArrayList();
    //create children
   
    //for each child in UI
        Child c = new Child();
        c.setParent(p);
        //TODO: get other properties from UI
        //add child to list
        children.add(c);
   //finally ADD the children ( NOT setChildren )
   p.addChildren(children);
   myDao.saveParent(p);
}