"Keola is the eldest of my family."
Translation:ʻO Keola ka hiapo o koʻu ʻohana.
ʻohana = family
It has been given both 0-class and A-class. If we are talking about members of our family and the group includes persons in the O-class group, we should use koʻu or the appropriate O-class possessive.
On the other hand, if someone is talking about only his or her wife or husband and children kaʻu would be the appropriate form.
(Page 182, Hawaiian Language Fundamentals ʻŌLELO ʻŌIWI, Hōkūlani Cleeland)