how to add two or more objects in single class at a time

Actually my addInvoice.Line is array which can hold multiple Line object, suppose two are
lineSalesItemLineDetail1, lineSalesItemLineDetail2 and one is DiscountLineDetail
following is my Request xml which i have to send to Intuit.Invoice class


129 2012-10-11 1 1 Large six foot ladder 124.00 SalesItemLineDetail 11 124 1 TAX 2 2 A green widgit 45.00 SalesItemLineDetail 4 15 3 TAX 294.00 DiscountLineDetail


in above xml i have 3 Line tag which kind of class in c#
and Invoice is class which contain Line array, but the problem is that invoice.Line cant hold all three line objects at time
it is holding last Line object anything. and Invoice.Line is a dll class which i can't edit.

following is my c# code :

 public bool CreateQBOInvoicReceipt(OnlineDataProcessingsImportClass.OnlineInvoiceQBEntry coll)
  {

  DataService dataService = null;

  OAuthRequestValidator oauthRequestValidator = new OAuthRequestValidator(CommonUtilities.GetInstance().AccessToken, CommonUtilities.GetInstance().AccessTokenSecret, CommonUtilities.GetInstance().ConsumerKey, CommonUtilities.GetInstance().ConsumerSecret);
  ServiceContext serviceContext = new ServiceContext("ec8e67fbb2ea3b4cf5ba225b33ab31ff1e6d", CommonUtilities.GetInstance().RealmId, IntuitServicesType.QBO, oauthRequestValidator);
  dataService = new DataService(serviceContext);


  Intuit.Ipp.Data.Invoice addInvoice = new Intuit.Ipp.Data.Invoice();
  OnlineInvoiceQBEntry Invoice = new OnlineInvoiceQBEntry();
  Invoice = coll;
  Intuit.Ipp.Data.SalesItemLineDetail lineSalesItemLineDetail = new Intuit.Ipp.Data.SalesItemLineDetail();
  Intuit.Ipp.Data.Line Line = new Intuit.Ipp.Data.Line();
  Intuit.Ipp.Data.Line DiscountLine = new Intuit.Ipp.Data.Line();
  try
  {
  #region Add Sales Receipt

  addInvoice.AutoDocNumber = true;
  addInvoice.AutoDocNumberSpecified = true;

  addInvoice.TxnDate = Convert.ToDateTime(Invoice.TxnDate);
  addInvoice.TxnDateSpecified = true;

  // find department
  foreach (var i in Invoice.DepartmentRef)
  {
  string displayname = i.Name;
  string id = string.Empty;
  ReadOnlyCollection dataDepartment = null;
  QueryService ItemQueryService = new QueryService(serviceContext);
  dataDepartment = new ReadOnlyCollection(ItemQueryService.ExecuteIdsQuery("select * from Department where Name='" + displayname + "'"));
  foreach (var item in dataDepartment)
  {
  id = item.Id;
  }
  addInvoice.DepartmentRef = new ReferenceType()
  {
  name=displayname,
  Value= id
  };
  } 

  addInvoice.PrivateNote = Invoice.PrivateNote; 
  //for adding line tag
  for (int runs = 0; runs < Invoice.Line.Count ; runs++)
  {
  foreach (var l in Invoice.Line)
  {

  if (l.LineDetailType == "SalesItemLineDetail")
  {
  Line.Description = l.LineDescription;

  foreach (var s in l.SalesItemLineDetail)
  {
  Line.DetailType = LineDetailTypeEnum.SalesItemLineDetail;
  Line.DetailTypeSpecified = true;

  string displayname = string.Empty;
  string id = string.Empty;
  foreach (var i in s.ItemRef)
  {
  displayname = i.Name;
  ReadOnlyCollection dataItem = null;
  QueryService ItemQueryService = new QueryService(serviceContext);
  dataItem = new ReadOnlyCollection(ItemQueryService.ExecuteIdsQuery("select * from Item where Name='" + displayname + "'"));
  foreach (var item in dataItem)
  {
  id = item.Id;
  }
  lineSalesItemLineDetail.ItemRef = new ReferenceType()
  {
  name = displayname,
  Value = id
  };
  }


  if (l.LineAmount == null)
  {
  decimal unitPrice = Convert.ToDecimal(s.LineUnitPrice);
  decimal qty = Convert.ToDecimal(s.LineQty);
  Line.Amount = unitPrice * qty;
  Line.AmountSpecified = true;
  }
  else
  {
  Line.Amount = Convert.ToDecimal(l.LineAmount);
  Line.AmountSpecified = true;
  }
 

  lineSalesItemLineDetail.AnyIntuitObject = Convert.ToDecimal(s.LineUnitPrice);
  lineSalesItemLineDetail.ItemElementName = ItemChoiceType.@UnitPrice;

  lineSalesItemLineDetail.Qty = Convert.ToDecimal(s.LineQty);
  lineSalesItemLineDetail.QtySpecified = true;

  foreach (var taxCoderef in s.TaxCodeRef)
  {
  lineSalesItemLineDetail.TaxCodeRef = new ReferenceType()
  {
  Value = taxCoderef.Value
  };
  }

  Line.AnyIntuitObject = lineSalesItemLineDetail; 
  } 
 
  }

  if (l.LineDetailType == "DiscountLineDetail")
  {
  Intuit.Ipp.Data.DiscountLineDetail DiscountLineDetail = new Intuit.Ipp.Data.DiscountLineDetail();
  foreach (var discount in l.DiscountLineDetail)
  {
  Line.Amount = Convert.ToDecimal(discount.LineDiscountAmount);
  Line.AmountSpecified = true;

  Line.DetailType = LineDetailTypeEnum.DiscountLineDetail;
  Line.DetailTypeSpecified = true;

  DiscountLineDetail.PercentBased = Convert.ToBoolean(discount.PercentBased);
  DiscountLineDetail.PercentBasedSpecified = true;

  DiscountLineDetail.DiscountPercent = Convert.ToDecimal(discount.DiscountPercent);
  DiscountLineDetail.DiscountPercentSpecified = true;

  foreach (var account in discount.DiscountAccountRef)
  {
  string displayname = account.Name;
  string id = string.Empty;
  ReadOnlyCollection dataAccount = null;
  QueryService ItemQueryService = new QueryService(serviceContext);
  dataAccount = new ReadOnlyCollection(ItemQueryService.ExecuteIdsQuery("select * from Account where Name='" + displayname + "'"));
  foreach (var item in dataAccount)
  {
  id = item.Id;
  }
  DiscountLineDetail.DiscountAccountRef = new ReferenceType()
  {
  name = displayname,
  Value = id
  };
  }
  Line.AnyIntuitObject = DiscountLineDetail;
  //addInvoice.Line = new Intuit.Ipp.Data.Line[] { Line };
  } 
  }

  addInvoice.Line = new Intuit.Ipp.Data.Line[] { Line };
 
  } 
  } 
 
  addInvoice.Deposit = Convert.ToDecimal(Invoice.Deposit);
  addInvoice.DepositSpecified = true;


  #endregion
  }
  catch (Intuit.Ipp.Exception.IdsException ex)
  {
 
  }

  Intuit.Ipp.Data.Invoice InvoiceAdded = dataService.Add(addInvoice);
  if (InvoiceAdded.domain == "QBO")
  {
  CommonUtilities.GetInstance().TxnId = InvoiceAdded.Id;
  CommonUtilities.GetInstance().SyncToken = InvoiceAdded.SyncToken;
  return true;
  }
  else
  {
  return false;
  }
  }



Please help me how to assign Line , if you can..

Thank you

How about this:

if (l.SalesItemLineDetail.Count > 0 && l.DiscountLineDetail.Count > 0)
{
    Line.AnyIntuitObject = lineSalesItemLineDetail;
    DiscountLine.AnyIntuitObject = DiscountLineDetail;
    addInvoice.Line = new Intuit.Ipp.Data.Line[] { Line, DiscountLine};
}  
else if (l.SalesItemLineDetail.Count > 0)
{
    Line.AnyIntuitObject = lineSalesItemLineDetail;
    addInvoice.Line = new Intuit.Ipp.Data.Line[] { Line }; 
}
else if (l.DiscountLineDetail.Count > 0)
{
    DiscountLine.AnyIntuitObject = DiscountLineDetail;
    addInvoice.Line = new Intuit.Ipp.Data.Line[] { DiscountLine};
}