Sasha:
UPD: I can provide you with some history of the last name but it's all in Russian
Thank you, Sasha. My Russian is not great, but I would like to try it with the information you have. Please post it here or in "Private Message". Thanks!
Wroclaw:
Have you checked Ship's Records for the arrival of your G-Grandfather. The ships manifest will show his original place of residence ?
Thanks, Wroclaw. I've searched for Ship manifest records, but haven't come up with anything yet. The town of origin is in or around "Uoginai", but I believe there were relatives also in Siuliai and Kaunaus/Kovno.
I have no idea what Uoginai is like now (city/town, etc.), but from family stories, I think it is rural.
I understand that the JewishGen site has records for Jewish and non-Jewish families, but could it be that Dowgiallo is a Jewish name, or might there be a Jewish branch of the Dowgiallo family? (Any Jewish Dowgiallos out there?)