Hi.

My opinion is that the right family name was Chiavàro instead of "Chiavarro". (look where falls the accent)

This is one of the biggest family in Paglieta and I don't know any Chiavarro.

For Nicola, starting from your approximative birth date, I think that he was husband of Anna Maria Di Nelli.
He was father of:
1870 Lorenzo
1877 Lenora

His parents were Lorenzo Chiavaro (1815) and Anna Antonia Di Genni (18??)
His brother were Pietrangelo (1842) father of Giovanni (1870)

The "surname" to this branch of Chiavaro Family name was "Nutare". One possible meaning can be "Notary".
Maybe in this family there was an ancestor with this profession.

These infos are taken from one of my books.
The years are approximation of 1 year, but all the events are to verify. I cannot warrant nothing.

Regards