So I just wanted to make sure i know how her ability works.

if my opponent has 1 card in their hand and i use KOF2006 We both add 1. since my opponent has no cards in his hand fio's ability doesnt go off right? and my opponent doesnt get the cards from their momentum?

correct, it has to be your(Fio's) ability adding the card and not another card's effect,

N.J.