I'm reviewing an Italian birth record # MSBF-LZX and need help

Hoopes Fred Russell

Record 25 is typical of many of the birth records I'm reviewing. Between 1808 and 1818, the records may give the father's first name and his father's last name, the mother's first name and her father's last name, and the child with no last name.

According to the rules, I can't index any last names. Can someone give me clarity on what is the most correct thing to do?

thank you very much