He did not receive any screen credit for his work in adapting Bride of Frankenstein. He adapted a story written by Agatha Christie for the movie Love From A Stranger (1947).
MacDonald and Michael Hogan adapted the novel Rebecca by Daphne du Maurier, from which Robert E. Sherwood and Joan Harrison created the screenplay for Rebecca, the 1940 film. Sherwood and Harrison were nominated for an Academy Award.