Runaway Island (1984)

Australia 1830. Jemma and Jamie McCloud are left behind on their father's farm with their aunt Agatha. Lachlan McCloud sails to England to ask attention from the government to do something about the corruption in New South Wales. While he's away aunt Agatha sells the farm and the two children are left homeless. Jemma and Jamie are told that their father drowned at sea. They meet Red Tom and Nipper and are determined to find their father's will.