Complex sentence: The children's situation was, after all, dubious; they were not only wictims of the witches which had kidnapped them to Blockula; there, they had also swored themselwes to the Devil, eaten his food and had sex.
Split into simpler sentences: The children's situation was, after all, dubious; they were not only victims of the witches which had kidnapped them. They had also sworn themselves to the Devil, eaten his food and had sex.