>Konstantin had a brother called "Boli." ...
In Lithuanian language there is no such name. It could be (in Lithuanian transcription, do not use english pronoucations of these names): Balys, Balislavas, Baliukas...
I tried to question my father (b.1918), but it is difficult to speak with him... So new info, my fathers father Juozas had a brother Jonas. This Jonas in his youth emigrated to Brasil and returned home only in 1950...1970? Was quite old ~80.
No other information about Matas parents or brothers. As I remember my father 20 years ago tried to contact St. Peterburg (Leningrad) legal authorities but no data were retrieved. 1917-1918 year were quite crazy for St. Peterburg and Russia :) - revolution and civil war means something.
I don't have the birth and death data of Matas. Need to visit cemetary.
P.S. Sorry for bad English- not native language.
http://www.savel.org