I watched two murder mysteries over the holiday (a Midsummer Murders and a Miss Marple) which both had the conceit that one of the central characters was not who he believed himself to be. Spoilers just in case:
One had had amnesia as a result of war wounds and the other was substituted as a child.
But it got me thinking, what exactly does happen in these cases? Do you lose any inheritances you’ve received? Are due to receive? What about pensions? Legal paperwork? I’m sure there are many other missing aspects of interest.
Off hand, I can’t think of a case exactly on point - a case where the misidentified person was an innocent. The cases of kidnapped infants being raised by the kidnapper comes close, but I’m not sure what the law would say about inheritance in those cases.
I suspect, by the way, that novels about this kind of situation are fictionalizations of the famous Tichborne claimant case (which did turn out to be a fraud) Tichborne case - Wikipedia
Try googling for switched at birth stories. I remember one about two girls, where one died of a genetic condition, and that was how it was found out. They were just kids when it was found out, so there were custody issues and all of that. I’m sure there are many other cases you can find.
There were two famous cases a few years ago where two babies were switched at the hospital just after birth. In one case the parents of one of the switched babies died only a year or so later in an car accident. In the other case the parents of one of the switched babies got divorced a decade or so later. In both cases there was a DNA test because somebody claimed the child wasn’t the father’s baby. In both cases the DNA test showed that the child wasn’t related to either the father or mother. In both cases they then checked all the babies born around the same time in the same hospital. In such cases, the problem was what was the best interest of the child - going back to their biological family or staying with the ones who had raised them.
While rare, there are the occasional amnesia cases. The only one I know of off-hand is Jody Roberts/Jane Dee. She was a newspaper reporter in Tacoma who disappeared and was eventually found living in Alaska. You can google her names for more (she has no Wiki page). Last time I looked into this, I found a report that she’d left her husband (don’t remember if it was divorce or just separation) and moved to her parents in Oregon.
The main legal issue I can think of for amnesia cases is if the person had been married before amnesia and then got married again after. That doesn’t apply in the above case since she was unmarried before. Have no idea what the law does in such situations.