Those days marriages were "pre-approved" by both families, so if the wife's family was a well known well established family then the husbands family was also of the same standard. You can also start your search from a different angle, the wife's family. Many Greeks don't understand that less than 10% of Greek males and females had a surname, the rest were only known by the fathers name or sometimes profession.
The accuracy of the information you have is also highly questionable.
He has siblings, George Zissimos Zizos. In Greek (those days) that translates to: GEORGE, SON OF ZISSIMOS, ZIZOS.
Than you mention another sibling called ZISSIMOS ZIZOS. (George's father's name?????)
Than you mention another sibling: Thomas Euthymios Zizos. That translates THOMAS SON OF EUTHYMIOS ZIZOS. Another father's name??
Is it possible that Thomas and George were 1st Cousins????
Another option I did not mention before is the possibility of the name being of Arabic origin. There is an arabic name (NOT MOSLEM) called AZIZ (male); AZIZA (female). AZIZ in Greek is AZIZOS -> ZIZOS.
There are hundreds of Arabic names used in Greece, for example Mora-i-tis (from Murat), etc.
Mareno = Marino from the Venetian name MARIN (known in Greece as Thalassinos). Marin is a very old (over 800 years old) family, well established in Greece.