Complex sentence: He married, secondly, Eleanor Baston in 1770 (at St Andrew's, Holborn), with whom he had two children, the elder of whom was Thomas Danvers Worgan, subsequently a musicologist.
Split into simpler sentences: He married, secondly, Eleanor Baston in 1770 (at St Andrew's, Holborn). He had two more children with Eleanor, the elder of whom was Thomas Danvers Worgan, subsequently a musicologist.