Interesting question OP because this has been going on in my mind for a while now. My 11 year old came to me a while ago and said she knew all those things weren't real, but thanked me for making it all so magical for her

, but my 9 year old I know doesn't believe but really plays it up, to the point where it actually annoys me, because I know she doesn't believe, but tries so hard to convince me that she does. I don't know but for some reason I feel like saying to her "ohhh come on you can stop with the antics, we all know he's not real"

, my 7 year old I think is in between and my 5 and 6 year old still believe.
I love Christmas and everything about Christmas and I never thought I would say this, but it will be so much easier when they all don't believe.