Complex sentence: Bysse was born around 1602, to Christopher Bysse (who was dead by 1615), an official of the Exchequer (as was John's grandfather), and Margaret Forster, daughter of John Forster, an alderman of Dublin.
Split into simpler sentences: Bysse was born around 1602, to Christopher Bysse (who was dead by 1615). Christopher was an official of the Exchequer (as was John's grandfather), and Margaret Forster, daughter of John Forster, an alderman of Dublin.