Complex sentence: Over half of Clarke's compositions remain unpublished, in the personal possession of her heirs, along with most of her writings; however, in the early 2000s more of her works were printed and recorded.
Split into simpler sentences: Over half of Clarke's compositions remain unpublished, and in the personal possession of her heirs, along with most of her writings. However, in the early 2000s more of her works were printed and recorded.