Complex sentence: It is not known whether Herrmann or the others bought the illusions directly from LeGrand or from another source, but they willingly performed the illusions after knowing that they were invented by Robert-Houdin.
Split into simpler sentences: It is not known whether Herrmann or the others bought the illusions directly from LeGrand or from another source. But they willingly performed the illusions after knowing that they were invented by Robert-Houdin.