How to WRITE (save) a flight plan? C# SDK

Questions & Community Discussions SimConnect
1

I can load the default MSFS FlightPlan with this code … (HOW DO I SAVE IT TO A FILE?)
public FlightPlan23 LoadFlightPlan23(string filePath)
{
var doc = XDocument.Load(filePath);
var flightPlanElement = doc.Element(“SimBase.Document”).Element(“FlightPlan.FlightPlan”);

var flightPlan = new FlightPlan23
{
    Title = GetElementValue(flightPlanElement, "Title"),
    FPType = GetElementValue(flightPlanElement, "FPType"),
    RouteType = GetElementValue(flightPlanElement, "RouteType"),
    CruisingAlt = double.Parse(GetElementValue(flightPlanElement, "CruisingAlt")),
    DepartureID = GetElementValue(flightPlanElement, "DepartureID"),
    DepartureLLA = GetElementValue(flightPlanElement, "DepartureLLA"),
    DestinationID = GetElementValue(flightPlanElement, "DestinationID"),
    DestinationLLA = GetElementValue(flightPlanElement, "DestinationLLA"),
    Descr = GetElementValue(flightPlanElement, "Descr"),
    DeparturePosition = GetElementValue(flightPlanElement, "DeparturePosition"),
    DepartureName = GetElementValue(flightPlanElement, "DepartureName"),
    DestinationName = GetElementValue(flightPlanElement, "DestinationName"),
    ATCWaypoints = flightPlanElement.Elements("ATCWaypoint").Select(e => new ATCWaypoint23
    {
        ID = e.Attribute("id").Value,
        ATCWaypointType = GetElementValue(e, "ATCWaypointType"),
        WorldPosition = GetElementValue(e, "WorldPosition"),
        SpeedMaxFP = double.Parse(GetElementValue(e, "SpeedMaxFP")),
        ICAOIdent = GetElementValue(e, "ICAO.ICAOIdent")
    }).ToList()
};
return flightPlan;

}

the class is this

public class FlightPlan23
{
public string Title { get; set; }
public string FPType { get; set; }
public string RouteType { get; set; }
public double CruisingAlt { get; set; }
public string DepartureID { get; set; }
public string DepartureLLA { get; set; }
public string DestinationID { get; set; }
public string DestinationLLA { get; set; }
public string Descr { get; set; }
public string DeparturePosition { get; set; }
public string DepartureName { get; set; }
public string DestinationName { get; set; }
public List ATCWaypoints { get; set; }
public FlightPlan23()
{

}

}

something starting with (i suspect)

doc.Save

thanks