I just always assumed that the "financial misfortune" applied to the entire family, since when wealthy families go bankrupt like that it tends to be a domino effect depending on how tight-knit the family is. That's why I originally postulated that whatever happened to make them loss all that money was at at most directly or at least indirectly related to why Emil couldn't pay for school. When we first meet them, Torbjorn say "we're" poor now" -- I took that we to mean him and the rest of the immediate family (brothers, sisters, nephews et al.)
Well, that whatever caused the loss of wealth affected the
entire family as far as we know it - read, the married couple Siv and Torbjörn and their kids on one hand, and Emil on the other - is all but said out loud in the comic. And considering that the legalese in
our day and age
doesn't allow clan liability makes the actual events ever more mysterious. Nonetheless, Siv calls the house in Mora "the only nice thing
we still possess", while Emil's official residence is still someplace else, even though he
already lived in the Mora house at one point. Also, no hint whatsoever that one side ever even tried to influence the other's ways of making a living (a.k.a. "get a
real payin' job ferchrissakes"). Hence my impression that even though a single event made them
all poor, they do
not consider themselves joint households (as our IRS would call it).