o.ListChildren

.BeginTransaction();
.SaveOrUpdate(o);
.CommitTransaction();

<?xml version="1.0" encoding="utf-8" ?>
<hibernate-mapping xmlns="urn:nhibernate-mapping-2.2">
	<class name="ContractWebService.Domain.Organization, ContractWebService" table="t_Organization" lazy="true">
		<id name="Id" column="Id" unsaved-value="0">
      <generator class="sequence">
        <param name="sequence">SQ_GLOBAL</param>
      </generator>
		</id>
    <property insert="false" update="false" type="DateTime" name="DateInsert" column="Date_Insert" />
    <property insert="false" type="DateTime" name="DateUpdate" column="Date_Update" />
    
    <property name="Name" column="Name" />

    
    <bag name="Supports" table="t_Support" cascade="all" inverse="true" order-by="DATE_END">
      <key column="ID_ORGANISATION" />
      <one-to-many class="ContractWebService.Domain.Support, ContractWebService" />
    </bag>
    
  </class>
</hibernate-mapping>

<?xml version="1.0" encoding="utf-8" ?>
<hibernate-mapping xmlns="urn:nhibernate-mapping-2.2">
  <class name="ContractWebService.Domain.Support, ContractWebService" table="t_Support" lazy="true">
    <id name="Id" column="Id" unsaved-value="0">
      <generator class="sequence">
        <param name="sequence">SQ_GLOBAL</param>
      </generator>
    </id>
    <property insert="false" update="false" type="DateTime" name="DateInsert" column="Date_Insert" />
    <property insert="false" type="DateTime" name="DateUpdate" column="Date_Update" />
    

    <many-to-one name="Organization" column="ID_ORGANISATION"
      class="ContractWebService.Domain.Organization, ContractWebService" not-null="true" />
    
    <property name="DateEnd" type="DateTime" column="DATE_END"/>
    <property name="Cost" column="COST"/>
    <property name="DecisNote" column="DECIS_NOTE"/>
    
    
  </class>
</hibernate-mapping>