The 30th fairytale in Fairytale Forest, Efteling, is "The Six Swans".
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A King gets lost in a forest, and an old woman helps him, on the condition that he marry her beautiful daughter. The King has a bad feeling about this but accepts anyway. He has six sons and a daughter from his first marriage, however, and fears that the children will be targeted by his new wife; so he sends them away and visits them in secret.
The new queen and now stepmother, who has learned witchcraft from her mother, finds out about her six stepsons and decides to get them out of her way. She sews six magical shirts and goes to the hidden castle where the children are hidden for safety, then tosses the shirts over the boys and transforms them into swans.
The brothers can only take their human forms for fifteen minutes every evening. They tell their still human younger sister that they have heard of a way to break such curses: she must make six shirts out of asters (or nettles, depending on the retelling) and can't make a sound or shed a tear for six years or the spell will never be broken. The girl agrees to do this, dedicating herself solely to gathering the asters and sewing in silence.
