Complex sentence: Always profitable, the stable began losing money in the latter part of the 1960s, exacerbated by Christopher Chenery's illness and as such, Penny Chenery's siblings planned to sell the operation on his passing.
Split into simpler sentences: Always profitable, the stable began losing money in the latter part of the 1960s, exacerbated by Christopher Chenery's illness. Therefore, Penny Chenery's siblings planned to sell the operation on his passing.