Hello
il faut lire la doc, Le principe est clairement expliqué sur la page http://wp-types.com/documentation/user-guides/creating-post-type-relationships/
Autre lectures intéressantes
http://codeseekah.com/2012/02/14/one-to-many-relationships-in-wordpress/
http://wp.smashingmagazine.com/2011/11/03/native-admin-tables-wordpress/
http://wordpress.org/plugins/custom-list-table-example/
A+