It's my family memory that Luongo in Naples, Italy is as follows:
A Luongo was married and he had 7 children.
After his wifes dead, he remarried a woman who had 7 children.
He adopted these 7 children. I don't know what their original surname was before adoption.
My grandmother, Rose Petraca, married a Luongo in USA. Her mother and father were from Avelino, Italy.
I believe a great many left Italy due to the volcano eruption.