Can anybody help me name this Christmas Cartoon movie special?

It was a cartoon Christmas movie about a girl and a boy who were siblings. The girl was terminally ill or was disabled. I can not remember the girl`s name, but i think the boy`s name was Landon. They were both in one dream world where everything was Christmas themed and snowy. I recall a scene where they are in a castle and were sleeping in beds. and the covers/blankets were waffles. And there was a snowman in it, but i do not think his name was Frosty. The snowman wore a pair of sunglasses with a hat i think. And i also remember at the end of the dream he melts but then they wake up to see him outside the house window. I am not sure when it came out, but it looks close to around the 90`s from what i remember of the animation.

Thank you all in advance.