parent->child relation to parent->group->child
===

i have a legacy database (which is still used by another legacy application) where the group is denormalized and duplicated into the child rows

    table parent
    (
      id
    )
    
    table child
    (
      id
      group_id
      group_name
      group_Flag
      group_type
      name
    )

and i would like to map them to

    class Parent
    {
        public long Id { get; private set; }
        public ICollection<Group> Groups { get; private set; }
    }
    class Group
    {
        public long Id { get; set; }
        public string Name { get; set; }
        public GroupType Type { get; set; }
        public bool Flag { get; set; }
        public ICollection<Child> Childs { get; private set; }
    }
    class Child
    {
        public long Id { get; private set; }
        public string Name { get; set; }
    }

1. Is this possible?
2. How to do that in any of NHibernate's mapping methods (xml, MbC, Fluent, ...)