Complex sentence: In 1966, the Kennedy family repurchased the home from its private owner, Mrs. Pollack, and between the years 1966--1969, Rose Kennedy restored the house to her recollection of its 1917 appearance.
Split into simpler sentences: In 1966, the Kennedy family repurchased the home. From 1966 to 1969, Rose Kennedy restored the house to her recollection of its 1917 appearance.