Complex sentence: Once the Lisbon house is cleaned out and emptied, it is quickly sold to a young couple from the Boston area, and most of the Lisbons' personal effects are either thrown out or sold in a garage sale.
Split into simpler sentences: Once the Lisbon house is cleaned out and emptied, it is quickly sold to a young couple from the Boston area. Most if the items and personal belongings of the Lisbons are either thrown out or sold in a garage sale.