Della Duck was the twin sister of Donald Duck and the mother of Louie, Huey, and Dewey. In the 1930s comics Della sent Donald’s nephews (Louie, Huey, and Dewey) to stay with him because she was a pilot and she could not take care of them without the help of her husband (he was in the hospital for injuries after a firecracker went off under his chair).

After some time, the boys would go back to live with their parents, but they returned to live with Donald when Della was sent on an experimental space flight. Later Donald would adopt them without an explanation of what happened to their parents.

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