First, if you order anything OOP, there has to be a separate check. You aren't making extra work for the server, this is the method Disney has for doing it. Yes, you can use your DDE for any items not covered on the DDP. Of course, use your head a little--if you order an extra appetizer or dessert, be sure to tell the server which one to bill separately (and put the more expensive on the DDP!). If you have OOP purchases (alcohol, food items, glow cubes, or whatever), you will have a line on that check to add tip. The second check can be charged to your room, your credit card, or paid in cash.