package My::Actor;
...
My::Actor->has_many( 'roles', 'My::Actor::Role', 'actor' );

##</code><code>##

package Sub::Person;
use base qw(Super::Person);
__PACKAGE__->has_many( 'organisations', 'Sub::Organisation', 'person' );

##</code><code>##

package Super::Person;
use base qw(Class::DBI);
__PACKAGE__->table('people');
__PACKAGE__->has_many( 'sessions', 'Super::Session', 'person' );
...