Insert Row in a child table based on Foreign key using NHibernate

See more:

C#

ASP.NET

Scenario is: I have two tables in the DB Emp_Details and DependentList. Emp_Details is the primary table and DependentList is the child table. I'm trying to perform insert operation in DependentList using NHibernate.

My classes looks like:

public class Employee
    {
        public virtual Guid ID { get; set; }
        public virtual String Name { get; set; }
        public virtual int Age { get; set; }
        public virtual DateTime DateOfBirth { get; set; }
        public virtual decimal Salary { get; set; }
        public virtual string Location { get; set; }
        public virtual string Department { get; set; }
        public virtual IList<Dependents> UserDependents {get;set;}
   }

public class Dependents
     {
         public virtual Guid ID { get; set; }
         public virtual String Name { get; set; }
         public virtual int Age { get; set; }
         public virtual Employee Employee { get; set; }
         public virtual string Relation { get; set; }
    }

The mapping files are:
Employee:

<hibernate-mapping xmlns="urn:nhibernate-mapping-2.2" assembly="ModelObjects" namespace="ModelObjects">
  <class name="Employee" table="Emp_Details" >
    <id name="ID" column="EmpId" type="Guid">
      <generator class="guid.comb">
      </generator>
    </id>
    <property name="Name" column="EmpName" type="String"></property>
    <property name="Department" column="EmpDept" type="String"></property>
    <property name="Age" column="Age" type="int"></property>
    <property name="DateOfBirth" column="DOB" type="DateTime"></property>
    <property name="Salary" column="EmpSalary" type="Decimal"></property>
    <property name="Location" column="EmpLocation" type="String"></property>
    <bag name="UserDependents" table="DependentList" generic="true" inverse="true" cascade="all">
      <key column="EmpId"></key>
      <one-to-many class="Dependents"/>
    </bag>
  </class>
</hibernate-mapping>

Dependents:

<hibernate-mapping xmlns="urn:nhibernate-mapping-2.2" namespace="ModelObjects" assembly="ModelObjects">
  <class name="Dependents" table="DependentList">
    <id name="ID" column="DependentId" type="Guid">
      <generator class="guid.comb"></generator>
    </id>
    <property name="Name" column="DependentName" type="String"></property>
    <property name="Age" column="DependentAge" type="int"></property>
    <!--<property name="DateOfBirth" column="DependentDOB" type="DateTime"></property>-->
    <property name="Relation" column="DependentRelation" type="String"></property>
    <many-to-one name="Employee" column="EmpId" not-null="false" class="Employee" cascade="all" fetch="join"></many-to-one>
  </class>
</hibernate-mapping>

I'm absolutely new to NHibernate and I need to know how to insert a record into the dependents table using foreign key from employee table... Does the Mapping file specifies Foreign key automatically??

What I am trying to do is:

using (ITransaction trans = this.Session.BeginTransaction())
                {
                    try
                    {
                        this.Session.Save(value);
                        trans.Commit();
                        return true;
                    }
                    catch (HibernateException)
                    {
                        trans.Rollback();
                        return false;
                    }
                }

But this is throwing an exception:

could not update: [ModelObjects.Employee#be4d8f67-2b67-41b4-b6f0-a2cde2e0af76][SQL: UPDATE Emp_Details SET EmpName = ?, EmpDept = ?, Age = ?, DOB = ?, EmpSalary = ?, EmpLocation = ? WHERE EmpId = ?]

instead of inserting in DependentList it is trying to update Emp_Details table...
Please help me...