When Z sees any candle she has to blow it.
Which means she needs to make a wish on it.
She speaks her wishes aloud.
"I wish I had a jaguar."
"I wish I had a genie."
"I wish I were a grown-up."
"I wish I were a baby."
"I wish I had a clean house."
Keep on wishing, kid. One of those days, one of those is bound to come true.
(By the way, 4 year old child of mine, I found the lighter and stash of birthday candles in your closet. You will never find them again.)