It is possible, there is a theory that the children of Hamelin joined the crusades and perhaps some stopped there, however this is a remote theory.
There was however, a more plausible theory, and that was that the King of Hungary invited people-- Germans to come and populate the area. This is more likely where the Saxons came from, this invitation. They were to leave only after centuries.
Still the theory of the Pied Piper is an interesting one with the addition of the Saxons of Transylvania living in the region. This is similar to John Hyundai