Ideally, when usercontrolSameGroupPolicy is set to false/0, a survey owner can:

1. go to their Survey Permissions
2. add a User Group they do not belong to
3. set survey permissions for the User Group they don't belong to for their specific survey

This isn't the case, but modifying two lines in SurveyPermission.php, by adding the condition,

&& Yii::app()->getConfig('usercontrolSameGroupPolicy') == true

can fix this. The two lines are,

~ line 435
} elseif ($action == "setusergroupsurveysecurity") {
if (!in_array($postusergroupid, getUserGroupList()) / THIS LINE && Yii::app()->getConfig('usercontrolSameGroupPolicy') == true / ) {
throw new CHttpException(403, gT("You do not have permission to this user group."));
}
$postuserid = null;

and

~ 591
if (!$isInArray / THIS LINE && Yii::app()->getConfig('usercontrolSameGroupPolicy') == true / ) {
throw new CHttpException(403, gT("You do not have permission to this user group."));
}