FWIW, I think Brother's lawyers are really bad if they think they can do this with impunity. I'm not a lawyer, and of course I don't know your family's situation or if your grieving sibling had/has energy to fight them, but this sounds to me like something that the next-of-kin/a heir can call them on if they choose to. In particular, if this was in the US I think it's illegal to terminate the position and health coverage without offering COBRA, regardless of the reason. There would be very clear damages, and this additionally makes one view "the position no longer existed" skeptically. I was a potential juror in a civil wrongful termination case this month. (I got excused on the third day of jury selection.) This case went to court nine years after the event, so four years is not too late. My understanding is that in a civil case, your sibling would just have to convince a jury it's more likely than not your sister-in-law was terminated improperly. I wouldn't rule out a criminal case also.
FWIW, I think Brother's lawyers are really bad if they think they can do this with impunity. I'm not a lawyer, and of course I don't know your family's situation or if your grieving sibling had/has energy to fight them, but this sounds to me like something that the next-of-kin/a heir can call them on if they choose to. In particular, if this was in the US I think it's illegal to terminate the position and health coverage without offering COBRA, regardless of the reason. There would be very clear damages, and this additionally makes one view "the position no longer existed" skeptically. I was a potential juror in a civil wrongful termination case this month. (I got excused on the third day of jury selection.) This case went to court nine years after the event, so four years is not too late. My understanding is that in a civil case, your sibling would just have to convince a jury it's more likely than not your sister-in-law was terminated improperly. I wouldn't rule out a criminal case also.