Children's book with magic house of mirrors

[Liekki]

I am looking for a picture book I read as a child. It was about a couple of siblings - a brother and a sister - going to a carnival or fair or amusement park where they find a house of mirrors. When they walk out they found their bodies have changed according to the last mirror they looked in - I think one of them had become taller and the other had bigger hands.
They start telling their friends about it and soon every child starts to go there to change their appearance.
When some start to do it in order to cheat at sports and such, the parents of the town order all the children to go back to the house of mirrors and look in the mirror that turns them back to normal just before the carnival closes for the winter.
The original sibling couple do a last transformation though, in which one of them gets a long arm (to get better at throwing snowballs) and the other gets giant half-circle feet (to have an advantage at skating) and they have to stay like that all winter because the carnival is closed for the winter.
I think I read it before 2003.
HELP!

[Kate]

Was the book new when you read it, or was it published quite some time before that?

[Ayshe]

Maybe this one: https://www.amazon.com/house-mirrors-... ?

[Lobstergirl, au gratin]

Liekki, are you still looking for this or did you find it?