Ghintang, you can always request them for the passport since they wont send old passport to Nepal. I had requested mine to visit outside the USA by emailing them. They didnt reply the email but they send my passport in my return envelop. And after tracking my MRP in above link (Ark's link), I got to know it was in DC. And I send the old passport back along with return envelop to get the MRP. They dont inform you anything to send it back, you just have to send it back once you are done. It took almost a month to get my MRP after dispatching it from Nepal but everything worked out smoothly.