Complex sentence: In 1814, he established himself in Santarém, then again in Fundão, returning to Lisbon to marry his cousin, returning to Fundão where the couple lived until 1820, occupying themselves with agriculture.
Split into simpler sentences: In 1814, he established himself in Santarém, then again in Fundão. He returning to Lisbon to marry his cousin, returning to Fundão where the couple lived until 1820, occupying themselves with agriculture.