Thank you for the info Helen, I had seen that thread already and I had no idea either, especially since many others are doing it. This will be my last down payment sale, all other custom orders will need to be paid in full up front per Etsy's requirements. I was just wondering how the "Mark as Shipped" button actually worked, thinking maybe I had to put in a valid tracking number...and then the second payment would need a different tracking number. I know that right now the tracking numbers are optional, but anybody can hit a shipped button and still not ship their goods. Seems a little vague to me. Otherwise, I think this option will work really good for us! Good luck to everyone in your sales!