Complex sentence: Men of his own choosing, many of his extended family, were appointed to administrate these dependent houses; in time, a lasting monastic network--a monastic "familia"--was centred on the island, led by his successors.
Split into simpler sentences: Men of his own choosing, many from his own extended family, were appointed to administrate these dependent houses. In time, a lasting monastic network--a ecclesiastical "familia"--was centred on the island, and led by his successors.