Don't require both father and mother name

lib/mkmemberdirectory.php

@@ -111,7 +111,14 @@ END;
             $htmlmiddle .= "\n<h3 class=\"letterheading\">$currentletter</h3>\n";
         }
         $famhtml = "\n<div class=\"family\">\n"
-                . "\t<b>" . $f->getName() . "</b>, " . $f->getFather() . " and " . $f->getMother() . "\n";
+                . "\t<b>" . $f->getName() . "</b>, ";
+        if (!empty($f->getFather()) && !empty($f->getMother())) {
+           $famhtml .= $f->getFather() . " and " . $f->getMother() . "\n";
+        } else if (!empty($f->getFather())) {
+            $famhtml .= $f->getFather() . "\n";
+        } else if (!empty($f->getMother())) {
+            $famhtml .= $f->getMother() . "\n";
+        }
         if (!$f->getPhotoPermission()) {
             $famhtml .= "\t<span class=\"icon nocamera\"></span>\n";
         }