Complex sentence: The first meetings were held as a response to the death of Ewing Young who had extensive business dealings with many other pioneers but left no will; a probate court was needed to administer his estate.
Split into simpler sentences: The first meetings were held, in part, as a response to the death of Ewing Young. Young died without a will, and had extensive business dealings with many other pioneers; a probate court was needed to administer his estate.