How are which side of Fonzie's family is Chachi from? His Mom or his Dad's side?

I think it was his mother's side because wasn't Grandma Nussbalm (or however you spell it) both Fonzie and Chachi's grandmother? And she must've been his mother's mother (otherwise her name would've been Grandma Fonzarelli). So my guess is that Aunt Louisa (Chachi's mom) was Fonzie's mother's sister.

i don't know i remember that their grandmother said she was married 4 or 5 times