How to get xpath with indexing to update XML file dynamically C#

<?xml version="1.0" encoding="UTF-8"?>
<breakfast_menu>
<food>
    <name>Belgian Waffles
    <price>$5.95
    <description>
   Two of our famous Belgian Waffles with plenty of real maple syrup
   
    <calories>650

<food>
    <name>Strawberry Belgian Waffles
    <price>$7.95
    <description>
    Light Belgian waffles covered with strawberries and whipped cream
    
    <calories>900

<food>
    <name>Berry-Berry Belgian Waffles
    <price>$8.95
    <description>
    Belgian waffles covered with assorted fresh berries and whipped cream
    
    <calories>900

Belgian Waffles                my xPath== "breakfast_menu/food/name"
Strawberry Belgian Waffles     my xPath== "breakfast_menu/food/name"
Berry-Berry Belgian Waffles    my xPath== "breakfast_menu/food/name"

Belgian Waffles                my xPath== "breakfast_menu/food[1]/name"
Strawberry Belgian Waffles     my xPath== "breakfast_menu/food[2]/name"
Berry-Berry Belgian Waffles    my xPath== "breakfast_menu/food[3]/name"

using (XmlReader reader = XmlReader.Create(pathMain)) 
            {
                XmlNode nodeTemp;
                var elements = new Stack<string>();
                var pathX = string.Empty;
                var pathXTemp = string.Empty;
                string prevNodeType = string.Empty;
                string currNodeType = string.Empty;
                while (reader.Read())
                {

                    string dg = string.Empty;

                    if (!reader.IsEmptyElement == true)
                    {
                        currNodeType = reader.Name.ToString();
                        if ((reader.NodeType.ToString() == "EndElement") || (prevNodeType != currNodeType))
                        {
                            indx = 1;
                        }
                        switch (reader.NodeType)
                        {
                            case XmlNodeType.Element:
                                elements.Push(reader.LocalName);
                               
                                addtoStackPanel(reader.Name, reader.Value, pathMain, pathX, 0);
                                break;
                            case XmlNodeType.Text:
                                if ((reader.Value != "") && (reader.Name != "style"))
                                {
                                   

                                    pathX = string.Join("/", elements.Reverse());
                                    
                                    addtoStackPanel(reader.Name, reader.Value, pathMain, pathX, 0);
                                    //prevNodeType = reader.Name.ToString();
                                    break;
                                }
                                else
                                {
                                    break;
                                }
                           
                            case XmlNodeType.EndElement:
                                elements.Pop();
                                break;
                        }

                    }
                  
                }
            }