Headscratchers / Vicky the Viking

• What is the deal with Ylvie? Most of the time, she is supposed to be the Girl Next Door. But in the English dub of the newer series, she calls Vicky's parents uncle and aunt, and Halvar at one point explicitly refers to Ylvie as his niece. Is this a case of Related in the Adaptation? Or a weird case of Dub-Induced Plot Hole, where no one thought of the Unfortunate Implications they were adding?