Dear nathanF-2,
You have to change your query. You need sort by _wpcf_belongs_property_id custom field
_wpcf_belongs_NAME_id = parent post id
$children = get_posts ('meta_key' => '_wpcf_belongs_YOURCPTSLUG_id','meta_value' => $post->ID)
More info about Types CPT relationships at http://wp-types.com/documentation/user-guides/creating-post-type-relationships/
Please let me know if you are satisfied with my answer and if I can help you with any other questions you might have.
Regards,
Gen.