I saw a movie in the early 80's (I think) about a man who marries a woman while he is on a business trip away from his home. He doesn't tell his young daughters or all the people who work for him on his plantation. After they marry, they each fly to his home on separate planes and he is killed. The new wife arrives on his plantation? First and no one knows they are married. She winds up taking care of his home, land, daughters and those who work for him. I would like to find this movie and watch it again? It is not Out of Africa but it takes place in Australia or Africa or somewhere out in the middle of rough terrain. Can anyone help me with this?

It's The Last Frontier.