The Trouble is Not in Your Set - S6-E14
Trivia: Marion Ross guest stars as a woman who watches a lot of TV, but believes the characters are real people. In one scene she references the following show by naming people/characters: Oprah, Donahue, The Tonight Show with Johnny Carson, The Cosby Show, Dynasty, M.A.S.H., Dallas, Leave it to Beaver. The last character she names is "The Fonz", from Happy Days, which Ross also starred in as Mrs. Cunningham.
Answer: Being declared legally dead is called "death in absentia", meaning there is no evidence of death (i.e. a body), but the individual is presumed dead. This can happen to anyone, not just MIA soldiers. If a spouse petitions the courts to grant a divorce on the presumption of death and all criteria are meet, they are legally divorced and free to remarry. The return of the presumed dead would not change the divorce ruling. However, if a spouse does not go through the legal steps prior to remarrying, then the return of the presumed dead spouse would nullify and void the 2nd marriage immediately (and the remarried spouse could face bigamy charges).
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