Have you found marriages in the U.K. for the two couples? this will let us know whether to search under maiden or married names.
Wives of military personnel didn't always travel on the same ships as their spouses so they might be found travelling separately to the U.S.
Last of all, are all the people involved deceased? newspaper obituaries might give information on how and when they arrived in U.S. (friend's mother was a war bride and husband's obituary told the story of their courtship, marriage, etc.)
