Can you do a Joined Subclass in the Entity Framework version 1? How do you approach the issue?
Joined Subclass:
http://www.xylax.net/hibernate/joinedsubclass.html
http://www.redhat.com/docs/manuals/jboss/jboss-eap-4.2/doc/hibernate/Hibernate_Reference_Guide/Mapping_declaration-joined_subclass.html