<?php
App::uses('AppModel', 'Model');

/**
 * Product model
 */
class ProductSuggestion extends AppModel
{
	public $belongsTo = array(
		'Person',
		'Product',
		'Recommender' => array(
			'className' => 'Person',
			'foreignKey' => 'recommender_id'
		)
	);
}

<?php
App::uses('AppModel', 'Model');

/**
 * Product model
 */
class ProductSuggestion extends AppModel
{
	public $belongsTo = array(
		'Person',
		'Product'
	);
}

--- 
+++ 
@@ -8,6 +8,10 @@
 {
 	public $belongsTo = array(
 		'Person',
-		'Product'
+		'Product',
+		'Recommender' => array(
+			'className' => 'Person',
+			'foreignKey' => 'recommender_id'
+		)
 	);
 }
Define the recommender of a product.
