As William Forbes was nine when his father died, Trustees had to be appointed to manage the estates until he was 25. His mother, Agnes Forbes, widow of William (1743-1815) and his uncle David Forbes, accepted appointments as Trustees and Guardians of William's children and estates following his death in 1815. His uncles Robert Forbes and David Abercrombie and his father's friend, John Abercrombie all declined to be Trustees. William Forbes, WS, a cousin, acted for the Trustees in legal matters.