My parents did it in a really half hearted way, so that when they asked me to write down what I wanted from Grandpa Frost as a 5 year old, I remember thinking "oh I'm so sure it isn't real but it'd be nice if it was real, so let's just all go along with it". We continued it with even less effort re the tooth fairy, which my parents only found out about from me (and I found out from school). Idk I liked it. Like we're all playing along "just in case" or because "wouldn't it be nice"