Most Nepalese people don't know about this. The real Newars when this nation was
created 200 years ago, all the inhabitants living in the Kathmandu valley were Jyaphus (Jya ya phu) which means "We can Work". In those days almost all of them had their Last Name that represented their skill or work. Example: Manandhar = Veg. Oil producers, Nakarmi = Blacksmiths, Maharjan = Farm produce suppliers, Shakya = Jewelers, Dangol = fertilizer makers and so on.
If you don't believe, then participate in one of their "Jatras" and also research on how the temples were made. They weren't made by today's Newars like Shrestha, Joshi, or pradhans etc.

As the valley became populated with people after Kathmandu became the capital, from surrounding hills and southern plains, people tried to associate themselves with the Jyaphus. The most popular ones that came from the south was "Shresta" which is now called Shrestha. They worked as a middleman to supply goods in and out of the valley. Likewise "Paradhan" which is now called Pradhan worked as rice distributer. "Bhandari" and "Joshi" brahmans started to call themselves Rajbhandari and Joshi who worked as priests in hindu festivals. "Baidya" who were originally from India worked as Nurses for Jyaphus and are also called Vaidya these days.

You can also find these facts in the oldest library in Kathmandu near New Road Gate (Nepal Airlines building )