I don't quite understand what you're trying to do, but I can tell you that it may not work out the way you want. This line here:
Code:
stringToParse = stringToParse.Replace("[ORDERITEMS]", tv.OrderItems.ToString)
tv.OrderItems is a string array, so when you call its ToString method, you will get something like "System.String[]" instead of the actual strings in the array.