Complex sentence: Jane Irwin Harrison, who married William Henry Harrison Jr, was the daughter-in-law of William Henry Harrison, ninth President of the United States; she acted as his official hostess during his brief tenure in office, a month in 1841.
Split into simpler sentences: Jane Irwin Harrison, who married William Henry Harrison Jr, was the daughter-in-law of William Henry Harrison, ninth President of the United States. She acted as his official hostess during his brief tenure in office, a month in 1841.