The Enchanted Grove (1980)

Lizuca is only six years old, not much older than her pet dachshund Patrocle, when her mother dies and she is left to live with her grandparents on their farm. Before long, Lizuca's father comes to take her away to live with him and his new bride, a vile woman who considers children the bane of all existence. Lizuca and the dachshund escape the wicked stepmother and spend the night in a hollow tree, a tree that changes into an enchanted land where Lizuca (like Alice through the Looking Glass) discovers a world of characters in the form of bees, frogs, the four seasons, Snow White, her dwarves, and other fairy tale creatures. This magic place is threatened by the evil stepmother's plan to sell the grove that protects the secret land to developers -- a decision that puts the woman on trial before this perfidy can be realized.

Unfortunately the movie The Enchanted Grove is not yet available on HBO Max.