Hi, I'm posting the solution to the problems addressed with Edit Order plugin.

Eg. If You Edit and order when you hit the update button you get a blank page and an error log reporting a Call to undefined function GetRewardPoints()

If You have installed both You need to add some function in the \admin\includes\functions\extra_functions\reward_points_functions.php
Just before the /* at the end add:

PHP Code:
function GetRewardPoints($products)
{
    $reward_points=0;
    if(REWARD_POINT_MODE=='0')
    {
        foreach($products as $product)
         if(isset($product['qty']))
          $reward_points+=GetProductRewardPoints($product['id'],$product['attributes'])*$product['qty'];
         else
          if(isset($product['quantity']))
           $reward_points+=GetProductRewardPoints($product['id'],$product['attributes'])*$product['quantity'];
          else
           if(isset($product['quantityField']))
            $reward_points+=GetProductRewardPoints($product['id'],$product['attributes'])*$product['quantityField'];
          else
           $reward_points="RP Error";
    }
    else
    {
        global $order;
        
        $GlobalRewardPointRatio=GetGlobalRewardPointRatio();
        if(isset($_SESSION['cart']))
         $reward_points=zen_round($_SESSION['cart']->show_total()*$GlobalRewardPointRatio-REWARD_POINTS_ROUNDING,0);
         
        if(isset($order) && isset($order->info))
         if(REWARD_POINTS_ALLOW_TOTAL=='0' && isset($order->info['subtotal']))
          $reward_points=zen_round($order->info['subtotal']*$GlobalRewardPointRatio-REWARD_POINTS_ROUNDING,0);
         else
          if(isset($order->info['total']))
           $reward_points=zen_round($order->info['total']*$GlobalRewardPointRatio-REWARD_POINTS_ROUNDING,0);
    }
    return $reward_points;
}

function GetProductRewardPoints($products_id,$attributes=null)
{
    global $db;
    $reward_price=0;
    
    if(zen_get_products_price_is_free($products_id)==false || REWARD_POINTS_ALLOW_ON_FREE=='1') // Allow RP on free items (Admin settable)
    {
        $sql = "SELECT prp.point_ratio*p.products_price AS reward_points, prp.point_ratio, p.products_price, p.products_priced_by_attribute 
                FROM ".TABLE_REWARD_MASTER." prp, ".TABLE_PRODUCTS." p, ".TABLE_PRODUCTS_TO_CATEGORIES." p2c 
                WHERE p.products_id='" . $products_id . "'
                AND p2c.products_id='" . $products_id . "'
                AND ((prp.scope_id=p.products_id AND prp.scope='".SCOPE_PRODUCT."') 
                OR (p.products_id=p2c.products_id AND prp.scope_id=p2c.categories_id AND prp.scope='".SCOPE_CATEGORY."')
                OR (prp.scope='".SCOPE_GLOBAL."'))
                ORDER BY prp.scope DESC LIMIT 1;";
    
        $result=$db->Execute($sql);
    
        if($result)
        {
            if(zen_has_product_attributes($products_id,'false') && !$attributes)
             $reward_price=zen_get_products_base_price($products_id);
            else
             $reward_price=$result->fields['products_price'];
             
            //echo '['.$reward_price.'=';
            //print_r($attributes);
            //echo ']';
            
            $special_price=zen_get_products_special_price($products_id);
            
            if(REWARD_POINTS_SPECIAL_ADJUST=='1' && $special_price && !$attributes)
             $reward_price=$special_price;
        
            // Calculate attribute pricing
            //if($result->fields['products_priced_by_attribute']=='1' && $attributes!=null)
            if($attributes!=null)
             if(isset($attributes[0]['option_id']))
              foreach($attributes as $attribute)
               $reward_price+=CalculateRewardPointsOnAttribute($products_id,$attribute['option_id'],$attribute['value_id']);
             else
              foreach($attributes as $option_id => $value_id)
               $reward_price+=CalculateRewardPointsOnAttribute($products_id,$option_id,$value_id);
        }
    }

    //echo '::'.$reward_price.', '.$result->fields['point_ratio'].', '.REWARD_POINTS_ROUNDING.'::';
    $reward_points=($reward_price*$result->fields['point_ratio'])-REWARD_POINTS_ROUNDING;
    if($reward_points<0)
     $reward_points=0;
     
    return zen_round($reward_points,0);
}

function CalculateRewardPointsOnAttribute($products_id,$option_id,$value_id)
{
    global $db;
    
    if($attribute=$db->Execute("SELECT products_attributes_id, attributes_discounted, options_values_price, price_prefix FROM ".TABLE_PRODUCTS_ATTRIBUTES." WHERE products_id='".$products_id."' AND options_id='".$option_id."' AND options_values_id='".$value_id."';"))
     if(REWARD_POINTS_SPECIAL_ADJUST=='1' && $attribute->fields['attributes_discounted']=='1')
      $new_attributes_price=zen_get_discount_calc($products_id,$attribute->fields['products_attributes_id'],$attribute->fields['options_values_price'],1);
     else 
      $new_attributes_price=$attribute->fields['options_values_price'];
      
    return ($attribute->fields['price_prefix']=='-'?-$new_attributes_price:$new_attributes_price);
}

function GetRedeemRatio($customers_id)
{
    global $db;
    
    $sql = "SELECT redeem_ratio 
            FROM ".TABLE_REWARD_MASTER." prp, ".TABLE_CUSTOMERS." as c
            LEFT JOIN(".TABLE_GROUP_PRICING." as gp) ON (gp.group_id=c.customers_group_pricing)
            WHERE c.customers_id='".(int)$customers_id."'
            AND ((prp.scope_id='".$customers_id."' AND prp.scope='".SCOPE_CUSTOMER."')
            OR (gp.group_id=c.customers_group_pricing AND prp.scope_id=gp.group_id AND scope='".SCOPE_GROUP."')
            OR (prp.scope='".SCOPE_GLOBAL."'))
            ORDER BY prp.scope DESC LIMIT 1;"; 

    $result=$db->Execute($sql);

    if($result)
     return $result->fields['redeem_ratio'];
    else
     return 0;
}

function GetRewardPointsRedeemMaximum($order_total)
{
    $redeem_ratio=GetRedeemRatio($_SESSION['customer_id']);
    $order_total_points=zen_round($order_total/$redeem_ratio,0);

    if((double)REWARD_POINTS_REDEEM_MAXIMUM>0)
     if(strpos(REWARD_POINTS_REDEEM_MAXIMUM,"%")!==false)
      return zen_round($order_total_points*((double)REWARD_POINTS_REDEEM_MAXIMUM/100),0);
     else
      if($order_total_points>REWARD_POINTS_REDEEM_MAXIMUM)
       return zen_round(REWARD_POINTS_REDEEM_MAXIMUM,0);

    return zen_round($order_total_points,0);
}

function GetCustomersRewardPoints($customers_id)
{
    $result=GetCustomerRewardPointsRecord($customers_id);
    if($result)
     return (int)$result->fields['reward_points'];
    else
     return 0;
}

function GetCustomersPendingPoints($customers_id)
{
    $result=GetCustomerRewardPointsRecord($customers_id);
    if($result)
     return (int)$result->fields['pending_points'];
    else
     return 0;
}

function GetCustomersLastOrderID($customers_id)
{
    global $db;
    
    $orders_lookup_query="SELECT orders_id FROM ".TABLE_ORDERS." WHERE customers_id = '".(int)$customers_id."' ORDER BY orders_id DESC LIMIT 1";
    $orders_lookup = $db->Execute($orders_lookup_query);
    if(isset($orders_lookup->fields))
     return $orders_lookup->fields['orders_id'];
    else
     return 0;
}

function ExtractNumber($str)
{
    if(preg_match("/^[0-9]*[\.]{1}[0-9-]+$/",$str,$match))
     return floatval($match[0]);
    else
     return floatval($str);    
}

function GetOrderTotalsArray($called_by)
{
    global $order_total_modules;
    
    $order_total_array = array();
    $modules=$order_total_modules->modules;
    if(is_array($modules))
    {
        reset($modules);
        while (list(,$value)=each($modules)) 
        {
            $class=substr($value, 0, strrpos($value, '.'));
            if($class!=$called_by && isset($GLOBALS[$class]))
            {
                $output_backup=$GLOBALS[$class]->output;
                if(sizeof($GLOBALS[$class]->output)==0)
                 $GLOBALS[$class]->process();
                for ($i=0, $n=sizeof($GLOBALS[$class]->output); $i<$n; $i++)
                 if(zen_not_null($GLOBALS[$class]->output[$i]['title']) && zen_not_null($GLOBALS[$class]->output[$i]['text']))
                  $order_total_array[]=array('code' => $GLOBALS[$class]->code,'title' => $GLOBALS[$class]->output[$i]['title'],'text' => $GLOBALS[$class]->output[$i]['text'],'value' => $GLOBALS[$class]->output[$i]['value'],'sort_order' => $GLOBALS[$class]->sort_order);
                  
                $GLOBALS[$class]->output=$output_backup;
            }
        }
    }
    return $order_total_array;
}

function GetRewardPointAdvancedCalculateValue()
{
    $value=0;
    
    $module_list=GetRewardPointAdvancedCalculateTable();
    
    foreach($module_list as $module)
     if($module['action']=="Subtract")
      $value-=GetOrderTotalValue($module['module']);
     else
      $value+=GetOrderTotalValue($module['module']);
      
    return $value;
}

function GetOrderTotalValue($module)
{
    global $order;
    $value=0;
    
    if(isset($GLOBALS[$module]) && isset($order->info))
    {
        //print_r($GLOBALS[$module]->output);
        //$output_backup=$GLOBALS[$module]->output;
        //$order_info_backup=$order->info;
        //if(sizeof($GLOBALS[$module]->output)==0)
         //$GLOBALS[$module]->process();
        for($loop=0;$loop<sizeof($GLOBALS[$module]->output);$loop++)
         if(zen_not_null($GLOBALS[$module]->output[$loop]['value']))
          $value+=$GLOBALS[$module]->output[$loop]['value'];
                  
        //$GLOBALS[$module]->output=$output_backup;
        //$order->info=$order_info_backup;
    }
    return $value;
} 
It should work now