Simplify the following text for a Grade 8 native English-speaking person.
Original: He was adopted by Uesugi Shigesada , then daimyo of Yonezawa , and in 1767 he succeeded Shigesada .
Simplified: He was adopted by the daimyo of Yonezawa , Uesugi Shigesada . In 1767 he replaced Shigesada as diamyo .