Complex sentence: As a child, she contributed to the household by singing songs she had composed herself to the music of the harp in her parents' theatre, widely advertised as a wonder; the singing and music-making blind child.
Split into simpler sentences: As a child, she contributed to the household by singing songs she had composed herself to the music of the harp in her parents' theatre. She was widely advertised as a wonder: the singing and music-making blind child.