I did not list the (...) Kresowiaks
Correct me if I'm wrong, but my understanding is that ethnically Polish Kresowiaks should join Eastern European and Baltic Projects, because this is where their grandparents and great-grandparents are from. So they should join these Projects:
Ukraine and Belarus -
https://www.livingdna.com/en-gb/one-family/research/eastern-europe-caucasus-siberia
Lithuania and Latvia -
https://www.livingdna.com/en-gb/one-family/research/nordics-and-baltics
Many of them still reside in these countries, not all of them moved to Poland after the border changes of 1939-1945.
=============
This project seems to be based more on geographical origins than on ethnicities or nationalities.
I already joined it, and they asked me about the birthplaces of grandparents and great-grandparents, but they did NOT ask me about my ethnic or national identity. I think that both types of questions should be asked.
So Polish Kresowiaks will join the Projects for Ukraine, Belarus, Lithuania and Latvia, but will indicate their ethnic or national identity as Polish (or mixed Polish-XYZ). At the same time, Germans from present-day area of Poland will join the Polish Project, but will indicate their ethnic identity as German (or mixed German-Polish).
Maciamo,
You should tell them to add questions about national or ethnic identity to their survey.
In addition to questions about birthplaces of grandparents and great-grandparents.
===============
There is a Polish minority even in Estonia (they are also one of Kresowiak groups):
http://polishgenes.blogspot.com/2014/02/genetic-affinities-of-estonian-poles.html