Complex sentence: Chantilly is an unincorporated community in western Fairfax County in Northern Virginia and a census-designated place (CDP), however a portion of Chantilly is located within the South Riding, Virginia CDP located to the immediate west, but within Loudoun County, Virginia.
Split into simpler sentences: Chantilly is an unincorporated community in western Fairfax County in Northern Virginia and a census-designated place (CDP). A portion of Chantilly is located within the South Riding, Virginia CDP located to the immediate west, but within Loudoun County, Virginia.