The Twilight Time release has commentary indicating that she was a non-professional, cast on the island. I think they said she married well.
http://www1.screenarchives.com/title_detail.cfm/ID/28645/THE-BOUNTY-1984-SPECIAL-PROMOTION/
It was supposed to be two pictures with two scripts; they shot most of the first script (voyage, mutiny the open boat voyage) and a much small part of the second (the mutineers on Tahiti and Pitcairn, and the capture and trial of the men who stayed on Tahiti.)
One of the commentaries is by a historian; the film is much more faithful to the truth than any other version, and more than most so-called "based on a true story" films.