Well there IS a way, a DNA-test called Autosomal dna, where "they" can check relatives from all sides of a persons families, many generations back.
If they could check Larissas dna against a database were they have a lot of members dna-registred, maybe there would be a match.
( I know this from personal experience, because I have done DNA-tests, and when I got the results I had 9 pages with -previously-unknown "cousins"! Then I got another
9 pages ! So I´m really busy every evening with "family" nowadays !
I am doing this for genealogy, with my cousins, because we are on a "hunt" for a couple of "missing" great great grandfathers !
Haven´t found them yet, but a lot of people who are decendants from one of our greatgrandfathers MATERNAL line-which I have never checked at all. And our common ancestors lived around 1650-1750 ! )
So, if one is lucky, there is a possibility.
(And there are DNA -forums which are especially dedicated to Nobility, Russian and Polish among them.)
But of course, there has to be a lot of people involved, church-and judicial (spell?) authorities among them.
Regards,
Tamara