diff --git a/dblayeroo.php b/dblayeroo.php
index 1331f6e..92c269c 100644
--- a/dblayeroo.php
+++ b/dblayeroo.php
@@ -1336,7 +1336,8 @@ class dblayeroo
     $this->debugLog ("Entering setForeignObj (OBJECT)");
     if (! is_object ($object))
       $this->DBException ("Invalid setForeignObj parameter: not an object");
-    if (! is_subclass_of ($object, __CLASS__))
+    if (! is_subclass_of ($object, __CLASS__) &&
+        get_class ($object) !== "dblayeroo")
       $this->DBException (
         "Invalid object provided to setForeignObj (not dblayeroo object)");
     if (! isset ($object->table))
@@ -1581,7 +1582,8 @@ class dblayeroo
       $this->DBException ("Invalid joinType provided to join (not known)");
     if (! is_object ($object))
       $this->DBException ("Invalid object provided to join (not object)");
-    if (! is_subclass_of ($object, __CLASS__))
+    if (! is_subclass_of ($object, __CLASS__)  &&
+        get_class ($object) !== "dblayeroo")
       $this->DBException (
         "Invalid object provided to join (not dblayeroo object)");
     if ($this->dsn !== $object->dsn)
@@ -1628,18 +1630,6 @@ class dblayeroo
     // fields of object
     $this->joins[] = "$joinType JOIN ".
       $this->sep.$object->tableprefix.$object->table.$this->sep." ON $tmp";
-    // Correct the WHERE in the main with the object WHERE
-    $this->whereExpression = array_merge ($object->whereExpression,
-                                          $this->whereExpression);
-    $this->whereValues = array_merge ($object->whereValues, $this->whereValues);
-    // Add the new object fields to the this. The fields must be available to
-    // be normalized at the end
-    $tmp = array ();
-    foreach ($object->fields as $key=>$data)
-    {
-      $tmp[$this->sep.$object->tableprefix.$object->table.$this->sep.".".
-           $this->sep.$key.$this->sep] = $data;
-    }
     return $this;
   }
   /* }}} */
@@ -1763,6 +1753,56 @@ class dblayeroo
   }
   /* }}} */
 
+  /** Get the WHERE clause of the object.
+    * If the joinObject is set, return all the WHERE clauses
+    */
+  public function whereGetExpression ()
+  /* {{{ */
+  {
+    $whereExpression = $this->whereExpression;
+    if ($whereExpression === null)
+      $whereExpression = array ();
+    if ($this->joinObject !== null)
+    {
+      foreach ($this->joinObject as $obj)
+      {
+        $exp = $obj->whereGetExpression ();
+        if (count ($whereExpression) && count ($exp))
+          $whereExpression[] = "AND";
+        if (count ($exp))
+          $whereExpression[] = "(";
+        $whereExpression = array_merge ($whereExpression,
+                                        $exp);
+        if (count ($exp))
+          $whereExpression[] = ")";
+      }
+    }
+    return $whereExpression;
+  }
+  /* }}} */
+
+  /** Get the WHERE values of the object.
+    * If the joinObject is set, return all the WHERE clauses with AND and
+    * parenthesis
+    */
+  public function whereGetValues ()
+  /* {{{ */
+  {
+    $whereValues =  $this->whereValues;
+    if ($whereValues === null)
+      $whereValues = array ();
+    if ($this->joinObject !== null)
+    {
+      foreach ($this->joinObject as $obj)
+      {
+        $whereValues = array_merge ($whereValues,
+                                    $obj->whereGetValues ());
+      }
+    }
+    return $whereValues;
+  }
+  /* }}} */
+
   /** Add a new ORDER sort. The multiple ORDERS are used from the first added to
     * the last added
     * @param string $field The field to sort
@@ -1927,8 +1967,9 @@ class dblayeroo
       $sql .= " $displayColumns\n FROM $this->sep$this->tableprefix".
               "$this->table$this->sep";
       $sql .= "\n ".$this->joinsGet ();
-      if (! empty ($this->whereExpression))
-        $sql .= "\n WHERE ". implode (" ", $this->whereExpression);
+      $whereGetExpression = $this->whereGetExpression ();
+      if (! empty ($whereGetExpression))
+        $sql .= "\n WHERE ". implode (" ", $whereGetExpression);
       if (count ($order))
         $sql .= "\n ORDER BY ". implode (",", $order);
       if (! empty ($this->limitExpression))
@@ -1964,8 +2005,9 @@ class dblayeroo
       break;
     case "DELETE":
       $sql = "DELETE FROM $this->sep$this->tableprefix$this->table$this->sep";
-      if (! empty ($this->whereExpression))
-        $sql .= " WHERE ". implode (" ", $this->whereExpression);
+      $whereGetExpression = $this->whereGetExpression ();
+      if (! empty ($whereGetExpression))
+        $sql .= "\n WHERE ". implode (" ", $whereGetExpression);
       if (! empty ($this->orderExpression))
         $sql .= " ORDER BY ". implode (",", $this->orderExpression);
       if (! empty ($this->limitExpression))
@@ -1987,8 +2029,9 @@ class dblayeroo
         $sql .= $this->sep.$key.$this->sep."=:".$hash;
         $i++;
       }
-      if (! empty ($this->whereExpression))
-        $sql .= " WHERE ". implode (" ", $this->whereExpression);
+      $whereGetExpression = $this->whereGetExpression ();
+      if (! empty ($whereGetExpression))
+        $sql .= "\n WHERE ". implode (" ", $whereGetExpression);
       if (! empty ($this->orderExpression))
         $sql .= " ORDER BY ". implode (",", $this->orderExpression);
       if (! empty ($this->limitExpression))
@@ -2014,7 +2057,7 @@ class dblayeroo
     $text = "";
     if (!$textForm)
       $st = self::$instance[$this->dsn]->prepare ($sql);
-    foreach ($this->whereValues as $hash=>$val)
+    foreach ($this->whereGetValues () as $hash=>$val)
     {
       $field = $val["field"];
       $value = $val["value"];
@@ -2364,7 +2407,7 @@ class dblayeroo
     }
     $this->debugLog ("Entering createRequest ()");
     $sql = $this->createRequest ();
-    $this->debugLog ("Entering prepareRequest (",$sql,", ",false,")");
+    $this->debugLog ("Entering prepareRequest (XXX, ",false,")");
     $st = $this->prepareRequest ($sql, false);
     $this->debugLog ("'",$this->getDisplayQuery (),"'");
     $st->execute ();