Petronella - a kind witch from an apple tree

Petronella is not an ordinary witch, but kind and cheerful. And she does not live in any hut in a dark forest, but in a magic house on an apple tree, in the center of the fruit garden, not far from the mill. That mill stood without a owner for many years, until one day a whole family, but what a noisy one!
At first, Petronella was expecting all kinds of troubles from the new neighbors, but once two of the new settlers came to visit her and turned out to be pretty kids! These were the boy Louis and his sister Lina. From the first meeting, Petronell and the guys liked each other, and then made friends. Just in time, because without the help of a good witch, Luis and Lina would have nothing to dream of winning an important competition, but this is a long story