Go to your local municipality and get a 'relationship' (natedar) document of you and your father/mother. If you have one right now, it will be helpful. Not sure how long it will take to make one, you never know it might take a long time. If you don't have one, get one before you go there.
When you land in KTM, get a month visa at the airport but then after few days (with that document) you can go to the immigration office and get visa for a year straight for lot cheaper. I think it is $5 for a month.