It isn't rubbish questions. These are tricky immigration situation because u don't apply for kids citizenship during parents naturalization. I am not lawyer, but my understanding is, kids don't become citizen just because parents took naturalization. My understanding is that it only happens once they become adult and choose to take passport. As kids they are only eligible at this time and get passport as dependent/child of citizen. Keep in mind parents apply for kids passport, kids don't sign on it.  And if kids are born in nepal as son/daughter of natural born napali citizen, when they are borned, they have right to be natural (banshaj) born Nepali citizen as adult. So I still don't understand, how Nepali government can force any natural born citizen off from their basic right. One can't force kids out of their citizenship right , because of their parents decision to migrate. This is definitely tricky legal matter.

But for convince and no one have time, resource and energy to fight for messy legal systems in Nepal, it's just convinent to get US passport for all family and travel that way.