I can't get this to work with Subsonic 3
I have two tables "Blog" & "Category" with a mapping (joining) table with a composite primary key on both Primary Keys.
I have looked into SQLServer.ttinclude and to my understanding, it doesnt handle many-to-many in the first place!
Relationship properties will get created by the SubSonic template, but they will be from your Blog & Category tables to the joining table (rather than through to each other).
In one project, I made significant changes to the Classes & Context tt files in order to generate relationship properties across many-to-many tables.